UniData Communication Systems STARLOG 6529 Configuration guide

STARLOG
Automatic Evaporation
System
Model 6529
User Manual Supplement Revision E
6225 February 1, 2001
unidata
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Printed in Australia
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Contents
1 INTRODUCTION......................................1
1.1 Major Components Of Model 6529-1 ....................2
1.2 Superseded Models ..................................3
1.3 Automating Existing Evaporation Pans..................3
1.4 Logging Evaporation .................................3
1.5 Example of Logged Data ..............................4
2 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
3 EVAPORATION MONITORING TECHNIQUES .............11
3.1 Using Evaporation Pan Data ..........................12
3.2 Some Sources Of Errors In Evaporation Pans ...........12
3.2.1 Systemic Errors ...............................12
3.2.2 Operating Errors...............................13
4 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
5 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 ....................................25
5.4.2 Level Control Module ...........................26
Automatic Evaporation System
i
5.4.3 Fill System ...................................26
5.4.4 Drain System .................................27
5.4.5 Power Supply .................................27
5.4.6 Installing 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 Drain Pump..........................30
6 OPERATING THE SITE ...............................31
6.1 Software Requirements..............................31
6.1.1 Overview Of The 6529E Scheme..................31
6.2 Preparing To Log Data...............................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 Site Visits .........................................41
7.1.1 Preparing for the Site Inspection ..................41
7.1.2 Carrying Out The Site Inspection..................42
7.1.3 Initial Inspection ...............................42
7.1.4 Reviewing The Data............................43
7.1.5 Recovering The Data ...........................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 ...................................46
7.3.1 Overview ....................................46
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
UNIDATA
ii

1 INTRODUCTION
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.
Automatic Evaporation System
INTRODUCTION 1
Evaporation pan
with bird guard Water level monitoring
and control system
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 datalogger. Landline,
cellular, satellite and radio communicationlinks can be used to monitor data
and operate the site.
1.1 Major Components Of Model 6529-1
n
Water Level Monitoring And Control 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.
n
Evaporation Pan And Bird Guard
Model 6529C Evaporation pan 1200mm diameter, fibreglass.
Model 6529D Bird and leaf guard for Model 6526C.
n
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.
UNIDATA
2 INTRODUCTION

1.2 Superseded Models
This system supercedes the previous UNIDATA Model 6529-1 instrument.
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.
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.
Automatic Evaporation System
INTRODUCTION 3
1.5 Example of Logged Data
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UNIDATA
4 INTRODUCTION

2 SPECIFICATIONS AND DETAILS
Evaporation System
Pan Type: US Class A compatible.
Range: 30mm to 250mm. Pan empty to full.
Resolution: 0.2mm of evaporation or rainfall.
Accuracy: +/- 0.4mm
Level Reset: Programmable. Default reset to 200mm (+/- 1mm) at a
preset time each day. Also resets 10mm below the
overflow level.
Reset rate: 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: Internal diameter 1208mm, outside diameter 1290mm.
Depth 250mm.
Operating depth: 200mm.
Volume at operating
depth: 229 litres.
Material: Fibreglass. Internal surface gloss white. Pre-drilled with
two 20mm diameter holes for hose fittings.
Intake: Bulkhead fitting for 12.5mm ID hose. Connects level
gauge to stillwell.
Refill: Bulkhead fitting for 12.5mm ID hose. Connects level
control system to pan.
Pan weight: 12kg.
Mounting: Timber frame 1300 x1300. Treated plantation softwood.
Mounting weight: 20kg.
Automatic Evaporation System
SPECIFICATIONS AND DETAILS 5
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
200mm.
Connectors: Hose and fittings to connect to intake from stillwell.
Volumetric Flask
Material: Clear PVC graduated container.
Capacity: 2000ml
UNIDATA
6 SPECIFICATIONS AND DETAILS
Model 6529M
Level gauge Model 6529E
Drain pump
Model 6529D
Bird guard
Mounting pallet
Model 6529C
Evaporation pan Inlet hose to stillwell

2.2 Automatic Evaporation Recording
Model 6706A Aluminium Enclosure
Dimensions: 320mm x 300mm x 750mm (Width x Depth x Height).
Vertically sliding front door. With hole for (purchaser
supplied) padlock.
Material: 2mm aluminium sheet. Powder coat finish.
Mounting: 1300mm long galvanised steel pipe, 40mm diameter with
cap. Two U-bolt assemblies to suit pipe.
Model 6529G Stillwell Assembly
Dimensions: 370mm high, 150mm diameter, with sealed bottom.
Material: PVC pipe.
Stillwell Cap: PVC Cap predrilled for float system and 6541. Cap rotates
to allow rear of 6541 to be visible.
Connector: Bottom fitting for 12.6mm hose to evaporation pan.
Automatic Evaporation System
SPECIFICATIONS AND DETAILS 7
Model 6541-31
Precision water level instrument
with display.Rotate 90° to view
and check float pulley.
6541-31/C
Integrated Micrologger
(optional).Connect to
computer with a
9pincable.
Model 6706A
Aluminium enclosure for evaporation
system.“U” bolt to post.
Model 6529A-2
PVC stillwell assembly.
Model 6907B
12V battery.
Model 6529-1
Level control module.
Model 6529-1
Refill solenoid with filter.
Model 6904B
Solar Panel on
top of cabinet.
Model 6529A-3
Float system inside.
PVC 115mm float,
line, counterweight,
and offset guide pulley.
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 (LxWxD).
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
Solenoid: Goyen 10BWJ-CNBNT-61D7.
Maximum pressure 1000kPa.
Minimum recommended pressure 10kpa.
Spare parts kit: GOYEN KM1664.
UNIDATA
8 SPECIFICATIONS AND DETAILS

Low Pressure Application
Low pressure solenoid: GOYEN 10BL2-CNBNT-61D7 direct acting solenoid.
Maximum pressure: 70kPa.
Minimum pressure: 0kPa.
Recommended
minimum: 10kPa.
Spare parts kits: GOYEN KM1423.
Pump: Optional pump (same as drain pump) if gravity feed not
possible.
Inlet Hose: 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.
Drain Pump
Type: Marine bilge pump. Located in pan. Cable length 2 metres.
Power: 12 volts @ 1.2 amps.
Capacity: Maximum 20 litres/minute.
Housing: PVC enclosure attached to inside of pan.
Drain Hose: 12.5mm hose can be connected. Not normally supplied.
Power Supply
Power supply: Maximum 0.3 ampere hour/day with daily level reset.
Battery: Model 6907B 12 volt, 7 ampere-hour sealed lead acid
battery.
Charger: Model 6904B 12 volt, 2 watt solar panel on enclosure roof.
Regulated by circuit in level control system.
Automatic Evaporation System
SPECIFICATIONS AND DETAILS 9
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UNIDATA
10 SPECIFICATIONS AND DETAILS

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 including 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 day
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.
Automatic Evaporation System
EVAPORATION MONITORING TECHNIQUES 11
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 evaporation 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 10%-12% 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.
UNIDATA
12 EVAPORATION MONITORING TECHNIQUES

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 discolouring
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.
Automatic Evaporation System
EVAPORATION MONITORING TECHNIQUES 13
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UNIDATA
14 EVAPORATION MONITORING TECHNIQUES

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.
·
If the 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 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.
Automatic Evaporation System
SITE REQUIREMENTS AND LAYOUT 15
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 supplied 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.
UNIDATA
16 SITE REQUIREMENTS AND LAYOUT
Optional Model
6529B Water
Temperature
Instrument
Water Supply
Model 6529E Water
Level Control System
Optional Model
6506A Rain
Gauge
Mounting
Pole
Model 6529A Water
Level Monitoring
System
Model 6529C
Evaporation
PanonPallet
6m x 6m fenced enclosure located in full sun with free air flow
To Equator
Water Drain
to waste or
recycling
Level monitoring
flow

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.
Automatic Evaporation System
SITE REQUIREMENTS AND LAYOUT 17
Reticulated
water mains
Shut-off valve
Model 6529-2H
High Pressure Solenoid
(10-100kPa)
mo
u
nt
ed
in
e
n
c
lo
su
r
e
Suppply hose with
valve at tank
1000 litre supply
tank on stand
Optional hose from
drain pump. Enters
top of tank to prevent
siphoning.
1metre
head
Model 6529-2L
Low Pressure Solenoid
(0-70kPa)
mounted in enclosure
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.
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.
UNIDATA
18 SITE REQUIREMENTS AND LAYOUT
Low level roof with gutters
to capture additional rainfall
Fill pump substituted
for solenoid
Drain pump hose outlet
configured to prevent
siphoning from pan
Buried tank for water supply
Ground
level

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
circulates freely beneath the pan, and that any leaks can be seen.
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 stillwell 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.
Automatic Evaporation System
INSTALLING THE EQUIPMENT 19
200mm
12.5m
m
hose
12.5mm hose
75mm
Point gauge assembly
in middle of pan Refill hose from water level control system
To water level monitoring system
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.
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.
UNIDATA
20 INSTALLING THE EQUIPMENT
approx.
850mm
1300mm
Solar Panel Your
padlock
Floor level 20mm
below the bottom
of the evaporation pan
Ensure the pole will not
shadow the solar panel

4. Put the 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.
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 hose 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.
Automatic Evaporation System
INSTALLING THE EQUIPMENT 21
Stillwell
6541-31/C (can be
rotated 90° on
stillwell)
m12.5 hose to
evaporation pan
Stillwell mounting
bracket and battery
shelf
Enclosure
SS hose clamp
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 of the floatline through the eye of the float. Use two
crimps to fix the loop.
- Place the float in the bottom of the stillwell. Thread the floatline up
through the centre hole in the stillwell cap. Place the cap and instrument
in position on the stillwell.
UNIDATA
22 INSTALLING THE EQUIPMENT

- 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.
2. Place the float onto the water surface in the stillwell.
3. 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.
Automatic Evaporation System
INSTALLING THE EQUIPMENT 23
Stillwell
Float pulley and
offset pulley on
rear of 6541
m12.5 hose to
evaporation pan
Float assembly:
float, line and
counterweight
Stillwell cap
Cut-away illustration of
float system in stillwell 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.
Switch
Number Switch Position Function
1 Off Direction of rotation to increase display as level rises.
2On
Direction of rotation to increase display as level rises.
3 Off Reserved.
4 Off Reserved.
5On
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.
8On
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 stillwell level will slowly adjust
to the new pan level. Confirm that the display moves in the same direction as
the pan water level changes.
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24 INSTALLING THE EQUIPMENT

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 powered 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.
Automatic Evaporation System
INSTALLING THE EQUIPMENT 25
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.
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 (½”) hose. This
hose enters the pan above water level to avoid any chance of water siphoning
back out of the pan.
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26 INSTALLING THE EQUIPMENT
Fill system
Drain system
Battery
Test power
Power from solar panel
Power for GSM MODEM
Signals from site data logger
1
16
TOP

A filter is located upstream of the solenoid. This has a removable element to
simplify cleaning. The filter connections suit a 12.5mm (½”) 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 (½”) 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 190mm 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.
Automatic Evaporation System
INSTALLING THE EQUIPMENT 27
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.
UNIDATA
28 INSTALLING THE EQUIPMENT

Control
Module
Terminal
Connected
Device To Remarks
1Fill System +Switched on to add water to evaporation
pan.
2-
3Drain System +Switched on to remove water from
evaporation pan.
4-
5Testing +Normally vacent . Plug in the fill or
draw system to test.
6-
7Battery +Connectes to rechargeable selaed klead
acid battery.
8-
9Solar Panel +Connects to solar panel.
10 -
11 GSM MODEM +Provides power for GSM MODEM (if
required).
12 -
6541-31C STAR-
LOGGER
PRO-
LOGGER
13 Data Logger
Relay control
signals
OUT0 Terminal 3 FTS 42 44
14 UPS
(OUT1) Terminal 1 FTS 47 45
15 External Power + Terminal 11 FTS 1 1
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(-).
Automatic Evaporation System
INSTALLING THE EQUIPMENT 29
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 supply 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.
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30 INSTALLING THE EQUIPMENT

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 Instrument 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.
Automatic Evaporation System
OPERATING THE SITE 31
6.2.1 To Adjust The Scheme Details To Suit Your Project
Select System from the toolbar and Scheme Editor from the drop-down menu.
Start your Starlog system and a list of schemes will be displayed. Select the
6529E Scheme from the Menu.
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.
UNIDATA
32 OPERATING THE SITE
Selecting the Scheme Editor.

Select the General Panel to change the description to your site name.
Automatic Evaporation System
OPERATING THE SITE 33
Displaying Editing Options.
The General Panel.
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.
Click on the Events panel 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.
UNIDATA
34 OPERATING THE SITE
The Events Panel.
The Program Panel.

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.
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).
When you have finished editing the Scheme, select Scheme from the toolbar,
then Save As.
Automatic Evaporation System
OPERATING THE SITE 35
The Log Buffer Panel.
The Events Detail Panel.
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
Connect your computer to the data logger using the correct 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.
UNIDATA
36 OPERATING THE SITE