Manual Automatic Evaporation System Model 6529
Contents
1. Check and adjust the computer time and date This will be used to reset the logger Carry any required spare parts and check instruments Take the visit file SITE VISITS AND MAINTENANCE 41 UNIDATA 7 1 2 Carrying Out The Site Inspection At the site your objectives are to Recover the recorded data and verify its quality and Ensure the site will keep operating correctly and the next period of data will be of good quality Your common sense will help you achieve this At times it will be better to do nothing and to return another day For example if it is raining heavily and the site has no protection you will damage the instruments and your test equipment if they get wet Rushing through a site visit or trying to use a faulty computer can also cause problems If you encounter a problem think logically through the process and carry out checks and tests to eliminate probable causes It is important to identify the real problem so it can be fixed Check the most obvious things first e g is your computer connected and operating properly Is the water supply functional Do not jump to conclusions Do not fiddle with things that are OK If it is working well leave it alone When you proceed prepare a comfortable and safe work environment for yourself lay out the tools and equipment you will need and work through your visit in a logical sequence such as suggested in the following section Fill in a report a2. Manual Evaporation Monitoring System Model 6529 eo Manual Automatic Evaporation System Model 6529 Revision History File name Revision Date Authors Previous version BX 2004 RS JH Unidata Manual 6529 Evaporation Monitoring System Issue 2 0 2007 AB CB JH MS KC Copyright Unidata Pty Ltd 2000 2008 All rights reserved No part of this publication may be reproduced transmitted transcribed stored in a retrieval system or translated into any spoken or computer language in any form or by any means Electronic mechanical magnetic optical chemical manual or otherwise without prior written permission of Unidata Pty Ltd 40 Ladner St O Connor Western Australia 6163 Unidata Manual 6529 Evaporation Monitoring System Issue 2 0 Automatic Evaporation System Contents INTRODUCTION logie Soe ae IM ead Pewee 1 1 1 Major Components Of Model 6529 3 2 1 2 Superseded Models 3 1 3 Automating Existing Evaporation Pans 3 1 4 Logging Evaporation 3 1 5 ErampleofLoggedData 4 SPECIFICATIONS AND DETAILS 5 2 1 Manual Recording System 5 2 2 Automatic Evaporation Recording 7 2 3 6529E Automatic Evaporation Recording And Level Control 8 EVAPORATION MONITORING TECHNIQUES
3. 1 4 Logging Evaporation A special instrument and scheme have been created within the UNIDATA software to monitor the recorded water level extract the evaporation and rainfall data and reset the pan water level These have been included with STARLOG v3 09E or later and are supplied on disk with initial releases of the instrument Alternatively you can obtain this update from the technical support section on the UNIDATA web site www unidata com au Refer to Software Requirements on page 31 for details on how to install the update This scheme offers you the options to log the raw water level total evaporation and total rainfall You can log either one daily total or measurements throughout each day The evaporation data accumulates all 0 2mm water level falls and the rainfall data all 0 2mm rises The effects of any pan water level resets and minor water level pulsations are not recorded INTRODUCTION 3 UNIDATA 1 5 Example of Logged Data Dix GpH increment Tat Lied TA Parii Sr 3 xe dt arr bai reaa ur BO if ER amh dg saria Heg I ye wm ONO i Pa was aH Don 1 i a amp HH 2 E a a T 7 a F a 7 E Li E 8 gp Po g P gg Sog P g P jg 35 9 5 5 Z amp B F f Cum mi Erir This page intentionally left blank 4 INTRODUCTION Automatic Evaporation System 2 SPECIFICATIONS AND DETAILS Evaporation System Pan Type Range Resolution Accuracy Level
4. 11 3 1 Using Evaporation PanData 12 3 2 Some Sources Of Errors In Evaporation Pans 12 3 2 1 Systemic Errors 12 3 2 2 Operating Errors 13 SITE REQUIREMENTS AND LAYOUT 15 4 1 Site Requirements For All US Class A Evaporation Pans 15 4 1 1 Water Supply 16 4 1 2 High Pressure Supply 16 4 1 3 Low Pressure Supply 17 4 1 4 Underground Supply 18 INSTALLING THE EQUIPMENT 19 5 1 Installing The Model 6529C Evaporation Pan 19 5 2 Installing The Model 6529A Enclosure 19 5 3 Installing The Stillwell Assembly 20 5 3 1 Connect The Stillwell To The Pan 21 5 3 2 Fill The Pan And Set The Water Level Instrument 22 5 3 3 Prepare The Float System And Stillwell Assembly 22 5 3 4 Install The Water Level Instrument 23 5 3 5 Set And Test The System 24 5 4 The Level Control System 25 5 4 1 OVErVIEW illie ee Ge RE ER eee W 25 5 4 2 Level Control Module 26 UNIDATA 5 4 3 Fill System sce ee eS A Rees 26 5 4 4 Drain System 27 5 4 5 Power Supply 27 5 4 6 In
5. 12 6mm hose to evaporation pan SPECIFICATIONS AND DETAILS 7 UNIDATA Hose 12 6mm heavy duty flexible hose 1 8 metres long Two stainless steel hose clamps supplied Hose guide PVC pipe 40m diameter and 1300mm long Model 6541 Water Level Instrument See the User Guide for the Model 6541 instrument for specifications Float system Float pulley 100mm circumference Offset pulley fitted Float 115mm PVC Counterweight 160 grams Floatline 0 4mm diameter stainless steel 690 mm long 2 3 6529E Automatic Evaporation Recording And Level Control 6912BR 12 Level Controller Circuit card with relays to operate fill solenoid and drain pump and a solar charge regulator for battery Enclosure UV stabilised polycarbonate IP67 Size 125mm x 75mm x 75mm L x W x D Terminals Pluggable terminal strip with terminals for fill solenoid drain pump solar panel battery and test Cables 1m cable to data logger terminal block of 6541 31 C 0 3m battery leads Fill Solenoid Type Solenoid valve with 10mm bore and nitrite seals Cable length 0 5m Power 12 volts 1 2 amps High Pressure Application High Pressure Goyen 10OBWJ CNBNT 61D7 Solenoid Maximum pressure 1000kPa Minimum recommended pressure 10kpa Spare parts kit GOYEN KM1664 8 SPECIFICATIONS AND DETAILS Automatic Evaporation System Low Pressure Application Low pressure solenoid Maximum pressure Minimum pressure Recommende
6. Resetting the Logger This is essential if the memory will not last until the next scheduled visit or if you have disconnected the logger power for any reason The reset erases all previous data and restarts logging You will have to process the data you have unloaded You can choose not to reset the logger Data logging will continue uninterrupted and you have secured a back up copy of the data When you unload data at your next site inspection you will retrieve all the previous data again plus the latest data all a one continuous file The previous back up can be discarded To reset the logger select Program Logger with Scheme to reset the logger The reset process is automatic and permanent 7 1 8 Final Site Check Use Scheme Test Mode to confirm that logging is underway and that the time and values are correct Note the information on your visit report Disconnect the computer and pack away your equipment 44 SITE VISITS AND MAINTENANCE Automatic Evaporation System Take a final look at the instruments and site Confirm that all is operational clean and in good condition with sufficient water battery power and logger memory to last until the next scheduled visit Close up the instrument cabinet and secure the site Pick up any rubbish and tidy the area 7 2 Data Processing And Management This is an essential but sometimes overlooked part of the site operation Valuable recorded data may be lost or misplaced unless a
7. UNIDATA 4 Place the instrument into its final position on the stillwell 5 Rotate it to a side on position With the floatline installed on both the float pulley and offset pulley check that the float and counterweight can rise freely from the bottom to the top of the stillwell without clashing or touching the sides 6 Rotate the instrument back to its operating position See the 6541 User Manual publication number 6209 for detailed information on the operation of the 6541 instrument Remove the front cover from the 6541 Confirm that the following transducer switch settings have been selected These are required for the correct operation of this instrument Number Position Function 1 Off Direction of rotation to increase display as level rises 2 On Direction of rotation to increase display as level rises 3 Off Reserved 4 Off Reserved 5 On Switches display to a resolution of 0 2mm 6 Off Switches display to a resolution of 0 2mm 7 Off Switch on only to reset to zero 8 On Internal battery On 5 3 5 Set And Test The System Adjust the level of the water in the evaporation pan to the exact level of the point gauge Turn on the 6541 and set the display to read 200 0 mm using the arrow keys To test the system use the measuring flask to add or remove water from the evaporation pan The display should change by 0 2mm for each 230 ml of water added or removed from the tank The
8. data processing system is established documented and used routinely after each site visit Some sites are operated for many years and ownership and operators may change A complete and documented data history is typically kept on a data processing file for the site The appropriate system will depend on the project It is possible to manage data from a small number of sites as spreadsheets provided the system is well organised and managed Larger networks require specialised systems and support The only copy of the data is the ASCII file on your computer hard drive This is why the backup copy has been left at the field site The original ASCII file should be archived as read only in a system that is regularly backed up This should be done immediately you return from the site visit This original file may contain anomalies that have to be edited out and periods of lost or faulty data Changes are made to a copy of the data never the original and comments about what was changed and why should be appended Blank periods or estimates if possible should be inserted if data has been lost These changes should be done by or in consultation with the site operator This edited data should then be appended to previous data to maintain a complete and continuous archive file of all data from the station Review this file to confirm that the latest data forms a sensible extension to previous data and that daily and seasonal evaporation and ra
9. of the floatline through the eye of the float Use two crimps to fix the loop Place the float in the bottom of the still well Thread the floatline up through the centre hole in the stillwell cap Place the cap and instrument in position on the still well 22 INSTALLING THE EQUIPMENT Automatic Evaporation System Cut away illustration of float system in stillwell Float pulley and offset pulley on rear of 6541 Tm s idu ae Stillwell cap counterweight Stillwell m12 5 hose to Thread the floatline over the instrument pulley then the offset pulley and loop it through the eye of the counterweight Adjust the length such that the counterweight eye is just above the side hole in the stillwell cap Use two crimps to fix the loop 5 3 4 Install The Water Level Instrument The 6541 sits on top of the stillwell The display normally faces the front The instrument can be rotated ninety degrees if you need to see the floatline at the back To install the 6541 instrument 1 Remove the rear sliding plate This is not required at these sites and there is not room to lift it off inside the enclosure Keep the rear plate for later use Place the float onto the water surface in the stillwell Rest the instrument on the side of the stillwell Thread the counterweight up through the centre hole in the cap over the pulleys and down through the outer hole INSTALLING THE EQUIPMENT 23
10. still well level will slowly adjust to the new pan level Confirm that the display moves in the same direction as the pan water level changes 24 INSTALLING THE EQUIPMENT Automatic Evaporation System 5 4 The Level Control System 5 4 1 Overview The purpose of the level control system is to reset the evaporation pan water level back to its reference level at a regular time each day You can set the reset time to suit your project This replicates the operation of a manual evaporation pan and produces similar data After operating for 24 hours the water lost to evaporation is replaced from a tank or other water supply If the pan is overfull from rainfall the excess is pumped from the pan This can be recycled back to the supply tank if site water is scarce The pan water level recorded by the data logger is used to control the reset At the specified time the logger will decide if water is to be added or removed It then switches on the appropriate device until the reference level is reached If the pan is in danger of overflowing from heavy rainfall the pan will also be reset A level control module consisting of a switch card in a polycarbonate enclosure controls the reset This switch card is operated by the site MICROLOGGER or by an associated STARLOGGER or PROLOGGER This card has relays with the capacity to operate either solenoids or small pumps Either device may be used depending on the site Power is supplied by a solar powe
11. the Scheme Reports A Scheme may have many Reports to display and save the data in a variety of ways Select Display a Data File Select the data plot report Review the logged data for the full period Look for any unusual data the may indicate a problem with the site or instruments Zoom the plots for details Check the general water level record to confirm the timing and level of the resets Check the detailed shape of the latest daily water level record for unusual periods that may indicate water leaks to or from the pan or the float system sticking or not functioning correctly Check that the derived evaporation is sensible with the expected diurnal variations SITE VISITS AND MAINTENANCE 43 UNIDATA 6 Check that the derived rainfall is sensible and supported by the evaporation data 7 Select the ASCII report The file will be saved in the Starlog Schemes folder as name A This is a flat ASCII file sited for spreadsheets and data processing systems 8 Copy the ASCII file to a disk and leave it at the site as a backup 7 1 6 Carry Out Tests And Maintenance Your data has now been recovered and secured You can now carry out any checks tests and maintenance required This data will be logged however it will be erased when you reset the logger before you leave Note on your visit report details of work you have done and maintenance required at the next visit See Section 8 for maintenance details 7 1 7
12. the enclosure 3 Remove clean and replace the filter element 4 Reassemble the system and check for leaks 7 8 5 Solenoid Pump Regularly check the operation of the solenoid and pump To check the condition and serviceability of the solenoid and or pump 1 Connect each device to the TEST position of the control module It should turn on and operate continuously 2 Measure the water flow from each device by timing the flow into the volumetric flask 3 Compare the flow test results with previous checks A significant reduction in the flow rate will indicate the need for cleaning or replacement 4 Check that the solenoid does not leak in the off position Service kits for solenoids are available from Goyen Valves or UNIDATA Spare pumps can be obtained from UNIDATA A spare solenoid and pump or service kits should be kept at the site ready for use SITE VISITS AND MAINTENANCE 47 UNIDATA This page intentionally left blank 48 SITE VISITS AND MAINTENANCE
13. with a spreadsheet to further analyse the data 38 OPERATING THE SITE Automatic Evaporation System 6 5 1 Interpreting Evaporation Data The following annotated graph is an example of typical data from a period and how it can be interpreted Three sets of data are logged The pan water level trace is a full record of all level changes You can analyse this and extract the evaporation and rainfall data you require However this has already been done for you and logged as the evaporation and rainfall data EDIC Ewapcrzisn intron Taat UFIDATA Parthi 3200 t 1H 1 Pan water level Rainfall Level reset after rainfall evaporation reset at 0100 each day No reset required isl ud zai Manual intervention to be removed from data Derived evaporation A Derived rainfall Peter die Date Fam PR ee Bun Kaa upp mip aed Huh cam The derived evaporation and rainfall data is the accumulated total since the logger was last reset It may contain corrupting events if there has been any artificial water level changes There are two shown in the above example These can be removed by editing the data in a spreadsheet or with one of a range of commercial editing systems OPERATING THE SITE 39 UNIDATA This page intentionally left blank 40 OPERATING THE SITE Automatic Evaporation System 7 SITE VISITS AND MAINTENANCE The purpose of installing the site is to obtain a co
14. 200mm Connectors Hose and fittings to connect to intake from stillwell Volumetric Flask Material Clear PVC graduated container Capacity 2000ml 6 SPECIFICATIONS AND DETAILS Automatic Evaporation System 2 2 Automatic Evaporation Recording Model 6706A Aluminium Enclosure Dimensions Material Mounting Model 6706A Aluminium enclosure for evaporation System U bolt to post Model 6541 31 Precision water level instrument with display Rotate 90 to view and check float pulley Model 6907B 12V battery Model 6529A 2 PVC stillwell assembly Model 6529 1 Refill solenoid with filter 320mm x 300mm x 750mm Width x Depth x Height Vertically sliding front door With hole for purchaser supplied padlock 2mm aluminium sheet Powder coat finish 1300mm long galvanised steel pipe 40mm diameter with cap Two U bolt assemblies to suit pipe Model 6904B Solar Panel on top of cabinet 6541 31 C Integrated Micrologger optional Connect to computer with a 9 pin cable Model 6529 1 Level control module Model 6529A 3 Float system inside PVC 115mm float line counterweight and offset guide pulley Model 6529G Stillwell Assembly Dimensions Material Stillwell Cap Connector 370mm high 150mm diameter with sealed bottom PVC pipe PVC Cap predrilled for float system and 6541 Cap rotates to allow rear of 6541 to be visible Bottom fitting for
15. 7 3 2 Site Surrounds 46 7 3 3 Evaporation Pan and Level Monitoring System 46 7 3 4 Input Water Supply 47 7 3 5 Solenoid Pump 47 Automatic Evaporation System 1 INTRODUCTION Evaporation pan Water level monitoring with bird guard and control system This supplement describes the installation and operation of UNIDATA s Model 6529 Automatic Evaporation System This is an advanced system that automatically operates an evaporation pan and records the evaporation and rainfall data The instrument is normally supplied as a complete package with a US Class A evaporation pan and all installation fittings It can be connected to any other type of pan The system is designed to operate for long periods without maintenance The water level transducer and data logger operate for one year from internal batteries The water level control system is solar powered The water supply to refill the evaporation pan is provided by the user from a tank or a reticulated water supply pipe Rainfall removed from the pan can be recycled if required INTRODUCTION 1 UNIDATA A water temperature sensor and a range of weather sensors can be added to identify the relationship between pan evaporation and site conditions This is required for evaporation and evapo transpiration studies and modelling An optional telemetry system can be connected to the datalo
16. 90mm above the pan bottom This prevents a malfunctioning pump from draining the evaporation pan 5 4 5 Power Supply The system is powered by a 12 Volt 7 Ampere Hour sealed lead acid battery This is recharged by a 12 Volt 2 Watt solar panel located on the top of the enclosure A regulator on the relay card maintains the battery in a fully charged condition This will power the level control system for an expected service life of at least three years The battery capacity is sufficient for up to two months of operation without recharging When the sun shines the solar charger can replace the typical daily power consumption within one hour INSTALLING THE EQUIPMENT 27 UNIDATA 5 4 6 Installing The Level Control System There is a row of 16 pluggable terminals on the level control module A strip of 8 terminals permanently connects the data logger GSM modem and solar panel Strips of two terminals are used to connect the battery and the drain and fill devices The Test socket is normally empty You can plug in the Drain or Fill device at any time to test it or to manually adjust the pan water level 28 INSTALLING THE EQUIPMENT Automatic Evaporation System Control Connected Module 4 To Remarks Terminal Device 1 Switched on to add water to evaporation Fill System pan 2 3 Switched on to remove wate
17. Reset Reset rate US Class A compatible 30mm to 250mm Pan empty to full 0 2mm of evaporation or rainfall 0 4mm Programmable Default reset to 200mm 1mm at a preset time each day Also resets 10mm below the overflow level Pumps 50mm out in 3 minutes Fills 3mm per minute with 10kpa 1m head Rate of refill increases as head increases 2 1 Manual Recording System Model 6529C Evaporation Pan Dimensions Operating depth Volume at operating depth Material Intake Refill Pan weight Mounting Mounting weight Internal diameter 1208mm outside diameter 1290mm Depth 250mm 200mm 229 litres Fibreglass Internal surface gloss white Pre drilled with two 20mm diameter holes for hose fittings Bulkhead fitting for 12 5mm ID hose Connects level gauge to stillwell Bulkhead fitting for 12 5mm ID hose Connects level control system to pan 12kg Timber frame 1300 x 1300 Treated plantation softwood 20kg SPECIFICATIONS AND DETAILS 5 UNIDATA Model 6529D Model 6529M Model 6529E Bird guard Level gauge Drain pump Model 6529C Mounting pallet Inlet hose to stillwell Evaporation pan Model 6529D Evaporation Pan Bird Guard Dimensions Outside diameter 1200mm Height 250mm Material Frame 8mm steel rod Mesh 12mm square steel mesh Finish Hot dip galvanised Weight 12kg Model 6529M Point Level Gauge Material PVC or Stainless Steel cylinder with point gauge at
18. UIREMENTS AND LAYOUT 17 UNIDATA 4 1 4 Underground Supply Where the water supply is scarce or inconvenient it is possible to install a tank large enough to be self sustaining at most sites Any excess rainfall captured in the pan can be recycled back into the storage tank A roof over the tank can be used to capture additional rainfall If required the tank can be buried and a small pump used to refill the pan Low level roof with gutters Drain pump hose outlet to capture additional rainfall configured to prevent A siphoning from pan m A Ground level Fill pump substituted for solenoid Buried tank for water supply The expected annual evaporation and rainfall and the monthly distribution can be estimated from published data from your national weather office This can be used to design the capacity of your supply tank 18 SITE REQUIREMENTS AND LAYOUT Automatic Evaporation System 5 INSTALLING THE EQUIPMENT 5 1 Installing The Model 6529C Evaporation Pan The evaporation pan should be located in the centre of the compound The pan is installed on an open timber palette constructed from timber treated with suitable preservatives The pallet should be firmly bedded into the natural surface with the top 50mm to 75mm above ground level Do not install the pan on a concrete bituminous or gravel pad It is essential that air
19. as trees bushes and buildings that will shade or shelter the site from wind The evaporation pan should be in the full sun Any obstruction should be at a distance from the pan of at least 4 times the height above the pan rim Select an area six metres square If necessary fence the area using an open fencing system with minimum wind resistance Maintain the ground cover within the fenced compound in a similar condition to the natural surroundings Keep vegetation trimmed to below the pan rim height SITE REQUIREMENTS AND LAYOUT 15 UNIDATA 6m x 6m fenced enclosure located in full sun with free air flow Water Supply Mounting Pole pit Model 6529E Water 7j ae Level Control System Model 6529A Water To Equator Optional Model Level monitoring Level Monitoring 6506A Rain flow 14 System i Gauge Water Drain 1 to waste or A recycling i Optional Model i 6529B Water i Temperature i Instrument 1 Model 6529C i Evaporation i Pan on Pallet 4 1 1 Water Supply The evaporation pan is refilled each day by the level control system The automated refill is controlled by a solenoid switched on by the datalogger in response to the level registered on the water level transducer The instrument must be permanently connected to a reliable supply of potable water Some typical examples are shown in the following sections Solenoids and pumps can be supp
20. ay and reading the total loss or gain in the pan water level and adjusting for the rainfall The pan water level is then reset to the operating level The UNIDATA evaporation system with level control is designed to simulate this daily operation This will produce data comparable with a manual pan EVAPORATION MONITORING TECHNIQUES 11 UNIDATA 3 1 Using Evaporation Pan Data The daily total evaporation can vary from 0 on a cool and misty day to more than 25mm on a hot dry and windy day Care must be taken in extrapolating the pan evaporation data to other sites or to estimating losses from natural water bodies For instance studies indicate that lake evaporation varies between 75 and 100 of pan evaporation depending on location and climatic conditions If there is a manual evaporation site in your region with a long history of evaporation data it is often possible to develop a relationship between the monthly and annual evaporation at the two sites With a reliable correlation based on several years of data you can theoretically extend the period of data from your site back in time using the historic data The pan data from your site can be used to estimate some aspects of nearby evapo transpiration only if the relationships are known or can be estimated These relationships can only be measured by controlled experiments Much research has been completed using US Class A pan data to estimate lake evaporation soil evaporatio
21. circulates freely beneath the pan and that any leaks can be seen Point gauge assembly Refill hose from water in middle of pan level control system 12 5mm hose To water level monitoring system Rest the pan centrally on the pallet Rotate it to orient the hole in the pan toward the location of the stillwell assembly Assemble the hose fittings through the hole at the bottom of the sidewall of the pan Seal the joints with a smear of silicon The assembled fitting has a hose barb on each side of the tank wall Install the Model 6529 C1 level gauge Attach the 550mm hose to the gauge and to the inside barb in the pan wall No hose clamps are used because very small leaks will not affect operation Position the level gauge in the middle of the evaporation pan 5 2 Installing The Model 6529A Enclosure The still well enclosure is located 1 5 metres from the pan on the side away from the equator where it will not shadow the pan Near the equator install it on the western side of the pan INSTALLING THE EQUIPMENT 19 UNIDATA Concrete the 40mm galvanised pipe firmly into the ground Attach the enclosure to the pole using the U bolts supplied Face the side with the hole for the stillwell hose toward the pan Move the enclosure up down the pole until the bottom is 20mm below the bottom of the evaporation pan Ensure the pole will not Solar Panel Your shadow the sola
22. d minimum Spare parts kits Pump Inlet Hose Drain Pump Type Power Capacity Housing Drain Hose Power Supply Power supply Battery Charger GOYEN 10BL2 CNBNT 61D7 direct acting solenoid 70kPa OkPa 10kPa GOYEN KM1423 Optional pump same as drain pump if gravity feed not possible 12 5mm heavy duty flexible hose 2 metres long to connect to tank Two stainless steel hose clamps supplied Inlet filter installed upstream of solenoid Marine bilge pump Located in pan Cable length 2 metres 12 volts 1 2 amps Maximum 20 litres minute PVC enclosure attached to inside of pan 12 5mm hose can be connected Not normally supplied Maximum 0 3 ampere hour day with daily level reset Model 6907B 12 volt 7 ampere hour sealed lead acid battery Model 6904B 12 volt 2 watt solar panel on enclosure roof Regulated by circuit in level control system SPECIFICATIONS AND DETAILS 9 UNIDATA This page intentionally left blank 10 SPECIFICATIONS AND DETAILS Automatic Evaporation System 3 EVAPORATION MONITORING TECHNIQUES Evapo transpiration is the endless cycle of moisture returning to the atmosphere to condense and fall again as rainfall Evaporation occurs from soil and water surfaces and transpiration from vegetation The energy that drives the process comes from solar and terrestrial radiation The rate is influenced by a complex interaction of many factors includ
23. g or deterioration with poor water quality 3 2 2 Operating Errors Evaporation pans are normally manually operated and require daily reading and resetting This is difficult or impossible at remote sites and data quality is compromised Water level too high will result in rainfall splashing or blowing from the tank when it is near full and overflowing when it is full Water level below the reference mark increases the shading from the sides of the tank and reduces evaporation by up to 2 5 10mm below the reference level in temperate regions Water level very low records increased evaporation as the temperature of water in the pan increases UNIDATA recommends these errors be avoided by automatically controlling the water level EVAPORATION MONITORING TECHNIQUES 13 UNIDATA This page intentionally left blank 14 EVAPORATION MONITORING TECHNIQUES Automatic Evaporation System 4 SITE REQUIREMENTS AND LAYOUT 4 1 Site Requirements For All US Class A Evaporation Pans Site requirements are frequently a compromise The following features are desirable when selecting a site They are listed in order of importance Ifthe site is near a water body or a spray irrigation or reticulation system it should be at least fifty metres away and on the prevailing upwind side The site should be secure from unauthorised interference and easy to access and service Select a level open site free from obstructions such
24. gger Landline cellular satellite and radio communicationlinks can be used to monitor data and operate the site 1 1 Major Components Of Model 6529 3 E Automatic Evaporation System Model 6529A Water level monitoring system for STARLOGGER Model 6529A C Water level monitoring system with integrated Micrologger to record data Model 6529E Automatic water level controller E Evaporation Pan And Bird Guard Model 6529C Evaporation pan 1200mm diameter fibreglass Model 6529D Bird and leaf guard for Model 6526C W Weather Monitoring Instruments Additional instruments that can be added to the Model 6529A C are Model 6529B Thermistor and float assembly to measure pan water temperature Model 6506A Tipping bucket rain gauge If the Model 6259A and STARLOGGER are used any additonal UNIDATA instruments can be added such as Model 6504FS Wind speed and direction Model 6501DU Air temperature relative humidity and solar radiation Model 7201A Net Radiation Model 6513A Soil Moisture Model 6522B Barometric Pressure 2 INTRODUCTION Automatic Evaporation System 1 2 Superseded Models This system supercedes the previous UNIDATA Model 6529 1 instrument which is now refered to as the Model 6529 1X 1 3 Automating Existing Evaporation Pans The evaporation instrument system and optional weather instruments can be added to any evaporation pan installation Contact your nearest UNIDATA support office for advice on upgrades
25. infall are sensible If apparent data problems are identified during data processing a note should be added to the station visit file to remind the site operator to attend to the matter at the next site visit The interaction between site operation data processing reporting and review allows for continuous improvement in the quality of the data produced SITE VISITS AND MAINTENANCE 45 UNIDATA 7 3 Site Maintenance 7 3 4 Overview All evaporation pans need regular maintenance It is recommended that sites with pans be serviced at least once a month Dust and debris will accumulate in the pan and algae can grow in some conditions Leaks can develop and water supplies may need regular maintenance The recorded data will be effected At sites in dry areas a bird guard will prevent water loss from birds and animals drinking from the pan The guards also reduce the amount of wind borne leaves and debris that lodge in the pan The water in the pan should be reasonably clear and clean If algae growth is excessive a commercial algaecide such as used for swimming pools may be added to the pan and supply tank 7 3 2 Site Surrounds At fenced sites the vegetation and ground conditions inside the compound should be similar to those outside Keep any bushes and grass around the pan trimmed to a level below the pan rim Bushes further away should not be higher than 25 of the distance from the pan Any fence should be of an open design wi
26. ing the topography geology and botany of the area the moisture content of the soil the moisture availability to vegetation and the local weather As many of these factors vary throughout each day and with the seasons the rates are continually changing at any given site Evapo transpiration is too complex to measure directly An evaporation pan is a practical way to measure the loss of water from a small water surface This is not a real measurement of any part of the natural evapo transpiration process Evaporation rates from lakes soil surfaces and vegetation will be different from a pan Historically many different shapes of evaporation pan and methods of installation have been used Different designs produce unique results If data from one pan is to be compared with another both pans must be the same To allow the standardisation of data and research across different sites and countries the World Meteorological Organisation WMO recommends the use of the United States Class A pan as a general purpose network instrument This type of pan is widely used in many countries The UNIDATA evaporation pan conforms to the dimensions of the US Class A pan Networks of US Class A evaporation pans are operated by many organisations in many countries The records can extend back for 50 years or more This data is typically a daily reading of the total evaporation This is measured manually by an observer visiting the site at the same time each d
27. l to open the listing of events Double click on event 3 if you wish to change the reset time Event 2 sets the level at which rainfall will be drained Event 3 sets the time at which the daily level reset will start PLESIPENI Zeus dst 3 2 ride Ej ejes al vent i Alange Gutguc Mana Force a Log Ha The Events Panel 34 OPERATING THE SITE Automatic Evaporation System The events detail box for event 3 will open This event sets the reset time when A B A is the TOD Time of Day and B is the required time 100 is 1 AM 1300 is 1 PM You can change the time and hit OK es zl estet Schema Mindrw Halo Hoy LO 2000 14 36 25 I LJ FL Melp Aijr X Enit EmLitlsg iSi The Events Detail Panel To select what to log open the Log Buffer panel Use the spacebar to select the data you wish to log at each log interval the spacebar toggles the X on and off The Log Buffer Panel When you have finished editing the Scheme select Scheme from the toolbar then Save As OPERATING THE SITE 35 UNIDATA You should save it with a scheme name that identifies your site This scheme must be used each time you connect to this data logger 6 3 To Start Logging Data E Nr E i GE ale Ee eS Aj seein Peal Mamet Simic ad Bor DO lari za di Sa ee AA eee eae ene Are ees progres Leger uLth dose Fl Bele LILE FELE 135 kia Connect your computer to the data logger using the c
28. lied to suit all applications 4 1 2 High Pressure Supply The simplest method is to connect to a reticulated water supply of potable water A pipeline is required to the site terminating in a tap or shut off valve A short length of m12 5 hose can be used to connect to the solenoid filter A high pressure solenoid with a range of 10 100kPa is available as an option 16 SITE REQUIREMENTS AND LAYOUT Automatic Evaporation System Model 6529 2H m High Pressure Solenoid 10 100kPa mounted in enclosure Reticulated Shut off valve water mains The maximum desirable pressure is 200kPa In some circumstances a pressure reducing valve may be required to prevent high pressure leaks 4 1 3 Low Pressure Supply The water supply can be from a mains system or a special storage tank The supply pressure should be between 10kpa 1 metre head and about 50kpa 5 metre head The supply is normally a tank that is refilled at regular intervals A 1000 litre tank will replace about 750mm of evaporation The tank capacity that you need depends on the expected evaporation at your site and when you can conveniently refill the tank 1000 litre supply tank on stand Optional hose from drain pump Enters top of tank to prevent siphoning 1 metre head Model 6529 2L Low Pressure Solenoid 0 70kPa Suppply hose with mounted in enclosure valve at tank 4 SITE REQ
29. m of the solenoid This has a removable element to simplify cleaning The filter connections suit a 12 5mm 2 hose from the supply tank A small pump may be operated if an underground water supply is used 5 4 4 Drain System A small pump is used to remove surplus water rainfall from the pan If the data logger detects the water level is higher than the reference at the reset time 0900hrs the pump is turned on until the level is correct The pump is also switched on to reset the pan level if rainfall increases the tank level to 240mm The pump has the advantage of moving the water quickly and being able to recycle it to a tank The pump mounts in a housing designed to stand within the evaporation pan and discharge water over the side through a 12 5mm 17 hose fitting A hose can be connected to this fitting to direct the pumped water to storage or away from the site The end of any drain hose should discharge into air at a higher level than the pan top to prevent water siphoning in or out of the tank The submersible bilge pump is installed inside a small housing made from PVC Terminals beneath the lid connect the pump with the cable to the control system The pump housing can be lifted from the well separated in the middle and the pump lifted out for cleaning The bottom of the pump can be removed to clean and service the impeller The pump must be inverted when installed for reliable self priming the inlet must be at about 1
30. n and local evapo transpiration Several different formulae and models have been developed to compute the potential evaporation based on solar radiation and weather data Experienced hydrologists can frequently determine reasonable relationships between pan evaporation and lake and soil evaporation from nearby areas of interest Pan evaporation is then the simplest way to carry out the basic long term monitoring Some additional soil moisture and weather data may be required for evapo transpiration monitoring 3 2 Some Sources Of Errors In Evaporation Pans 3 2 1 Systemic Errors Bird guards are required at many sites to stop animals drinking the water and to keep out wind blown debris These guards reduce the recorded evaporation by about 1096 1296 because the mesh and frame partially shades the water surface reduces the airflow and intercepts some rainfall UNIDATA recommends that measured evaporation data should be increased by 10 if a bird guard is used Water quality has a minor effect Seawater evaporates 2 to 3 less than fresh water Turbidity has no apparent effect 12 EVAPORATION MONITORING TECHNIQUES Automatic Evaporation System l UNIDATA recommends no adjustments are normally required Pan corrosion changes the interior surface colour and texture The difference between a black painted and unpainted galvanised iron pan is approximately 10 UNIDATA pans are constructed of white fibreglass to minimise discolourin
31. ntinuous and reliable record of pan evaporation This data may be used for a range of process management and environmental purposes sometimes in unexpected ways It is important that the site be operated to a consistent standard by staff with a basic understanding of data collection and management Although the equipment can operate for up to 1 year the site may deteriorate to an unacceptable condition within a few months Regular site checks and equipment servicing is essential The site should be inspected and serviced at least monthly The purpose of the site inspection is to check that the present data is accurate and that this will continue Experienced site operators prepare for the site visit and use a report form and checklist to record details of the visit Instrument manuals documents site access details special instructions and visit reports should be kept in a site file and taken to the site each visit Data should be regularly recovered from the site and securely archived in a system that will permanently preserve the raw data A copy of this data should be reviewed and edited to adjust any anomalies or errors and saved as an archive for future analysis and use 7 1 Site Visits 7 1 1 Preparing for the Site Inspection Do the following Check the report from the previous site visit Prepare to complete any special work that is required Check your computer Confirm you have an adequate power supply and the correct cable
32. orrect UNIDATA cable and then 1 Start the STARLOG V3 software 2 Select the scheme for the site 3 Select Program logger with scheme 4 Click OK to continue The scheme will be loaded and logging will commence automatically 36 OPERATING THE SITE Automatic Evaporation System 6 4 To Check Data While Logging Is In Progress Select Scheme Test Mode from the main menu for the scheme The screen that appears shows complete details of the current logging situation The display is updated each scan You can use this screen as often as you like and for as long as you like logging continues normally while in Scheme Test Mode kii Eel F1 N ls ili 7 Cim Camm CORS i SEn N L OPERATING THE SITE 37 UNIDATA 6 5 Data Recovery And Review Refer to the software manual for Version 3 Software for detailed descriptions on operating the software and displaying data Select Display a Data File from the menu The following screen allows you to select from a range of Reports that you have created and files you have unloaded 3 LIBRE Al m vean PERSA ms uem Prine ra mere Sen imu dmi Tear on Sal ane Boot dm Test on HHL RETHE EER KXaplraLium Teal Cus BANI D Select the display Select the unload file to view Plots will be displayed as requested and axes may be expanded and compressed 1 Test on T RM Fatal Pe AA La Sa UA P11 heel An ASCII file or Lotus file can be created and used
33. pply hose to the inlet of the filter Fit a tap or shut off valve at the water supply point Connect the solenoid lead and plug it into terminal 1 and 2 of the terminal strip You can test the solenoid operation by plugging in to the test position The solenoid should click open when you plug it in and click shut when you unplug it 5 4 9 Install The Drain Pump Stand the pump assembly in the pan near the inlet Direct the outlet fitting through the mesh of the bird guard You will have to cut out a small panel of mesh Attach the pump assembly to the mesh of the bird guard using the stainless steel hose clamp provided Run the cable alongside the inlet hose and into the cabinet through the cable gland provided Plug the pump cable into terminals 3 and 4 of the terminal strip To test the pump transfer the plug to the test position The pump should run when you plug it in and stop when you unplug it 30 INSTALLING THE EQUIPMENT Automatic Evaporation System 6 OPERATING THE SITE This instrument is operated in the same way as any other UNIDATA Instrument You use the same software to program and test the logger and unload and view data See the Version 3 Software Manual for detailed information 6 1 Software Requirements You will need a laptop computer a cable and Starlog Version 3 09E or later software You can obtain updates from the technical support section on www unidata com au A special Evaporation Instr
34. r from 2 Drain System evaporation pan 5 t Normally vacent Plug in the fill or 6 Testing draw system to test 7 Connectes to rechargeable selaed klead 8 Battery acid battery 9 t Connects to solar panel Solar Panel 10 11 Provides power for GSM MODEM if 12 GSM MODEM required STAR PRO 6541 31C LOGGER LOGGER 13 Data Logger OUTO Terminal3 FTS 42 44 Relay control UPS 14 signals OUTI Terminal 1 FTS 47 45 15 Terminal 11 FTS 1 1 External Power 16 Terminal 13 FTS 2 2 5 4 7 Install The Battery And Solar Panel Stand the battery on the bracket holding the stillwell Use the cable supplied to connect the battery to terminals 7 and 8 Bring the solar panel wires through the gland in the cabinet roof Mount the solar panel onto the top bracket with the two screws in the panel frame Use tamper proof screws if security is a concern Connect the solar panel to terminals 9 and 10 INSTALLING THE EQUIPMENT 29 UNIDATA 5 4 8 Install The Fill Solenoid Place the solenoid outlet through the front hole of the three at the bottom of the left hand wall of the cabinet Attach the hose to the pan and seal it with a hose clamp Connect the pan end of the hose to the fitting in the top hole of the pan and fasten it with a hose clamp Push the filter and short joiner hose through the hole in the opposite side of the cabinet Join the hose to the solenoid inlet with a hose clamp Connect your water su
35. r from the drop down menu Start your Starlog system and a list of schemes will be displayed Select the 6529E Scheme from the Menu ro Glee gj ela Al Panal Configure Windrw Help AT Fox Lrmtrumerc Editor Rir TT7 CET Editor LIr T5 Tart Trde ilia Calibrmtor Telemetry Al1tsFLDO Dm shel Kali WEE Tl Help 4l X Exit Edit The rurrznt scheme Selecting the Scheme Editor The following screen will open You may have to select Window option then All Options and Tile the Display for the most convenient display Click on the appropriate box to open it for editing 32 OPERATING THE SITE Automatic Evaporation System Displaying Editing Options Select the General Panel to change the description to your site name The General Panel OPERATING THE SITE 33 UNIDATA Select the Program Panel to edit the log interval and other details The following settings are recommended for a normal project You may prefer a 15 minute log interval to reduce the volume of logged data 2S Peed PULE UII lana Foes He g Se Al Echoes Mindowr Bele Mew 10 1000 Lian nara a os uo REDEINEIIITTHRTITCTENGTOME 8 utiera CLJ tirul 3 kime 00 Scan aca HiJa i Misra TY p mar Charge Xduacur LEVEL Level terest EEE inanir EVAR Evap RALIN Fain Tb Tii Dee kimara Geepas hara Force a The Program Panel Click on the Events pane
36. r panel padlock X A E x x qu ELLA LLL EEEE approx 850mm 1300mm SS Floor level 20mm below the bottom e ee of the evaporation pan uy 5 3 Installing The Stillwell Assembly Do the following 1 Leave the 6541 instrument off the stillwell during initial installation 2 Thread the 1 5 metre hose through the hole in the side facing the pan 3 Connect the hose to the barb fitting in the base of the stillwell Fix it with a hose clamp 20 INSTALLING THE EQUIPMENT Automatic Evaporation System 4 Putthe stillwell assembly into the enclosure It stands on the enclosure floor at the back Clamp the stillwell to the bracket with the stainless steel hose clamp supplied a 6541 31 C can be rotated 90 on stillwell o Enclosure Stillwell mounting IIIA bracket and battery shelf SS hose clamp Hd Stillwell m12 5 hose to evaporation pan ODS 5 3 1 Connect The Stillwell To The Pan A flexible hose is used to link the stillwell to the evaporation pan It is normally buried to protect it from accidental damage This hose ensures that the water level in the pan and stillwell are the same at all times An air lock could form in the hose if there are any high points This can restrict or block water transfer and prevent the system from operating correctly To keep the ho
37. red battery system A regulator on the switch card manages battery charging All devices connect to the row of pluggable terminals located at the front of the enclosure INSTALLING THE EQUIPMENT 25 UNIDATA 5 4 2 Level Control Module This self contained instrument is normally located near the battery and solenoid or pump There are no internal settings or adjustments A cable connects it to the site data logger terminals QO C 16 See page 29 for TOP pin connection 2 OJ The other components of the system plug into the marked terminals A Test terminal socket is provided This has continuous 12V power Plug in your fill or drain device if you want to test run it Contact your local UNIDATA support centre for advice if you wish to fit the controller to an existing instrument or use it for another purpose 5 4 3 Fill System A solenoid valve is normally used to turn on a water supply and add water to the evaporation pan This is typically turned on by the data logger at 0900 each day if the water level is low and turned off when the level is correct The solenoid is located in the base of the instrument enclosure The outlet of the solenoid is connected to the evaporation pan by a 12 5mm hose This hose enters the pan above water level to avoid any chance of water siphoning back out of the pan 26 INSTALLING THE EQUIPMENT Automatic Evaporation System A filter is located upstrea
38. s you go and complete one part of the procedure before proceeding to the next 7 1 3 Initial Inspection Before touching anything inspect and note the condition of the site installation and instruments Are there any signs of damage or interference s the pan water level OK s the water supply functional and sufficient to last to the next inspection Are the instruments clean dry and secure Is the water level transducer displaying the correct water level 42 SITE VISITS AND MAINTENANCE Automatic Evaporation System If you notice any problems try and work out what has happened and how to prevent it reoccurring 7 1 4 Reviewing The Data To review the data 1 Ch uEes cp 9 a Connect your computer to the data logger Start the STARLOG Version 3 Software Select the Scheme for the site Select Scheme Test Mode and review the display of present logging Note the logger time and date and any difference with real time Note the water depth in the pan the transducer display and the logged value Note the total evaporation and rainfall and the battery voltage Check the memory remaining and then estimate the expiry date Scan the recent data listed Look for any anomalies that may indicate faults 7 1 5 Recovering The Data To recover the data 1 Select Unload Data from Logger Data is saved in the Starlog Schemes folder as name U This is a binary file that can only be interpreted by
39. se straight sleeve it with a piece of 40mm PVC pipe before it is buried This also serves as a duct for the fill hose and the drain pump cable Lay the sleeved hose into a shallow trench between the stillwell and pan Cut the hose to length and connect it to the pan using a hose clamp INSTALLING THE EQUIPMENT 21 UNIDATA 5 3 2 Fill The Pan And Set The Water Level Instrument Fill the pan with water to near the reference point in the pan level gauge Check the hose connections and the pan for leaks and fix any problems Confirm that the water level in the stillwell is the same as in the evaporation pan and that they move together An airlock in the hose system can prevent this happening To check take some water from the pan and almost fill the stillwell Check that it drains back to the previous level If it doesn t clear the air lock To clear an airlock remove the hose from the level gauge and blow through it until it bubbles into the stillwell Replace the hose and confirm the water transfer is OK 5 3 3 Prepare The Float System And Stillwell Assembly Do the following 1 Bolt the Model 6541 31 C instrument to the stillwell cap with the two bolts provided The instrument must be fitted with a 100mm circumference float pulley and an offset pulley 2 Prepare the float system This is normally supplied as an assembly ready for installation However if you need to prepare it yourself follow these steps Loop one end
40. stalling The Level Control System 28 5 4 7 Install The Battery And Solar Panel 29 5 4 8 Install The Fill Solenoid 30 5 4 9 Install The DrainPump 30 6 OPERATINGTHESITE 31 6 1 Software Reguirements 31 6 1 1 Overview Of The 6529E Scheme 31 6 2 PreparingToLogData 31 6 2 1 To Adjust The Scheme Details To Suit Your Project 32 6 3 To Start Logging Data 36 6 4 To Check Data While Logging Is In Progress 37 6 5 Data Recovery And Review 38 6 5 1 Interpreting Evaporation Data 39 7 SITE VISITS AND MAINTENANCE 41 7 1 KA AA AI UU AA fans Bad Ga eA AAA 41 7 1 1 Preparing for the Site Inspection 41 7 1 2 Carrying Out The Site Inspection 42 7 1 8 Initial Inspection 42 7 1 4 Reviewing TheData 43 7 1 5 Recovering TheData 43 7 1 6 Carry Out Tests And Maintenance 44 7 1 7 Resetting the Logger 44 7 1 8 Final Site Check 44 7 2 Data Processing And Management 45 7 3 Site Maintenance AA aa A 46 7 3 1 Overview 46
41. th minimum wind resistance 7 8 8 Evaporation Pan and Level Monitoring System The evaporation pan will require regular cleaning The colour of the interior surface the water clarity and the amount of surface litter all affect the recorded evaporation The frequency of cleaning will depend on site and seasonal conditions The objective is to keep the pan reasonable clean throughout the year Floating material and debris may be scooped out with a small swimming pool net Clean any dust and debris from inside the pan The walls and bottom of the pan can be brushed and the water swirled into a whirlpool Loose material will accumulate in the centre of the pan and can be vacuumed off with a siphon hose If there is plenty of water at the site it may be simpler to drain clean and refill the pan 46 SITE VISITS AND MAINTENANCE Automatic Evaporation System Inspect all hoses and fittings and the stillwell assembly for signs of leaks Repair any problems 7 3 4 Input Water Supply There is a water filter between the solenoid and the input water supply hose This is to intercept any fine debris that may prevent the solenoid from closing The filter should be checked regularly It may be removed washed and replaced How often this will be required will depend on the quality of the water supply To clean or change the filter 1 Open the enclosure and grasp the body of the filter 2 Unscrew the filter cap located on the outside of
42. ument and Scheme have been created to monitor the recorded water level extract the evaporation and rainfall data and reset the pan water level This software is supplied on disk with initial releases of the instrument Copy the files 6529E to the Starlog Schemes folder PDL6529E SRC to the Starlog folder PDLTRANS MET to the Starlog Eng folder 6 1 1 Overview Of The 6529E Scheme This scheme offers you the options to log the raw water level total evaporation and total rainfall You can log either one daily total or details throughout each day The evaporation data accumulates all 0 2mm water level falls and the rainfall data all 0 2mm rises The data is logged in increments of 0 4mm The effects of any pan water level resets and minor water level pulsations are not recorded The time of the day at which the water level will be reset has been set to 0100 You may wish to change this to the Bureau of Meteorology standard of 0900 The level at which the rainfall will be pumped out to prevent overflow has been set to 240mm but can be adjusted 6 2 Preparing To Log Data Select the 6529E scheme This can be edited to your logging requirements and saved with your project name It can then be loaded to your logger and used to log unload and review data the same as any other Unidata project OPERATING THE SITE 31 UNIDATA 6 2 1 To Adjust The Scheme Details To Suit Your Project Select System from the toolbar and Scheme Edito
Download Pdf Manuals
Related Search