ISCO 674 User manual

Model 674 Rain Gauge
Instruction Manual
Part #60-3283-011
Copyright © 1992, 2001. All rights reserved, Isco, Inc.
Revision E, November, 2001

FOREWORD
This instruction manual is designed to help you gain a thorough understanding of
the operation of the equipment. Isco recommends that you read this manual com-
pletely before placing the equipment in service.
Although Isco designs reliability into all equipment, there is always the possibility
of a malfunction. This manual may help in diagnosing and repairing the malfunc-
tion.
If the problem persists, call or email the Isco Customer Service Department for
assistance. Contact information is provided below. Simple difficulties can often be
diagnosed over the phone. If it is necessary to return the equipment to the factory
for service, please follow the shipping instructions provided by the Customer Ser-
vice Department, including the use of the Return Authorization Number speci-
fied. Be sure to include a note describing the malfunction. This will aid in
the prompt repair and return of the equipment.
Isco welcomes suggestions that would improve the information presented in this
manual or enhance the operation of the equipment itself.
Contact Information
Phone: [phone] (USA, Canada, Mexico)
[phone] (Outside North America)
Repair Service: [phone] (Analytical and Process Monitoring
Instruments)
[phone] (Samplers and Flow Meters)
Fax: [phone]
Email address: [email protected]m
Website: www.isco.com
Return equipment to: 4700 Superior Street, Lincoln, NE 68504-1398
Other correspondence: P.O. Box 82531, Lincoln, NE 68501-2531

i
Table of Contents
Model 674 Rain Gauge
Section 1 Operation Instructions
1.1 Description and Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.2 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.3 Materials and Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.4 Location of the Rain Gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
1.4.1 Suggested Siting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
1.5 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
1.6 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
1.7 Electrical Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
1.8 Technical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
1.9 Replacement Parts List. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
List of Figures
1-1 Replacement Parts List Illustration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
List of Tables
1-1 Technical Specifications for the 674 Rain Gauge . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5

Model 674 Rain Gauge
Table of Contents
ii

1-1
Model 674 Rain Gauge
Section 1 Operation Instructions
1.1 Description and
Operation
The Isco Rain Gauge is a precision instrument for accurately
measuring rainfall. Using a tipping bucket, the rain gauge pro-
vides accurate measurement from 0.01 to 22 inches per hour.
The rain gauge is mounted inside a steel cylinder and has an
eight-inch opening on top to collect rain. Rain falls through a
screen into a funnel. From the funnel, rain collects in one side of
a two-chambered plastic bucket mounted on jewelled pivots.
When rain fills the chamber, the bucket tips, draining the water
and exposing the other chamber to fill. When that chamber fills,
the bucket tips back and the process begins anew.
Each time the bucket tips from one side to the other a magnet
passes over a reed switch, momentarily closing the normally
open contacts. This contact closure provides a short-duration out-
put pulse from the rain gauge for each 0.01 inch of rain.
1.2 Applications When connected to a flow meter, the rain gauge enables the flow
meter to print rainfall data on its chart or store rainfall data in
memory. It also lets the flow meter actuate an associated Isco
Automatic Wastewater Sampler.
Typical applications include monitoring of storm water runoff,
inflow and infiltration studies (I&I), and combined sewer over-
flow monitoring. You can also use the rain gauge for any other
general purpose rainfall measurement as long as the associated
equipment is electrically compatible.
1.3 Materials and
Construction
The rain gauge is constructed of steel, stainless steel, aluminum,
and plastic. All metal parts are coated, plated, or painted to
ensure a durable, ruggedly tough instrument capable of resisting
deterioration from exposure to the elements. Screens cover all
openings, preventing clogging by leaves, insects, or other debris.
The powder-coated steel sleeve protects the internal parts. The
jewelled-pivot mounting for the tipping bucket provides long life.
A built-in bubble level makes leveling the rain gauge after instal-
lation easy. A 50-foot cable terminated in an M/S connector
attaches the rain gauge to the flow meter or to other equipment.
CAUTION
The rain gauge is factory-calibrated and adjusted. Do not
attempt to make any adjustments to the jewelled-pivot screws.
You may damage the jewel bearings.

Model 674 Rain Gauge
Section 1 Operation Instructions
1-2
1.4 Location of the Rain
Gauge
Location affects the accuracy of the rainfall catch because the
prevailing winds may tend to carry the rain away from the
gauge. There are advantages and disadvantages to most sites.
Sites may be either open or protected. Totally open sites affect
the accuracy of the catch if the rain is carried on strong winds,
but are satisfactory if rainstorms are generally calm. With no
nearby vegetation the characteristics of the site will not tend to
change over time, which is an advantage. Where strong winds
are characteristic of storms, protected sites are generally prefer-
able. This is because the effect of the wind on the rainfall catch is
reduced. The presence of small groups of objects or objects of
varying heights around the gauge can also affect accuracy by pro-
ducing eddy currents in the wind which will interfere with the
catch.
1.4.1 Suggested Siting Groups of objects of uniform height (such as trees) in the vicinity
of the gauge are beneficial for an accurate catch by acting as a
windbreak while not interfering with the catch. Mounting the
rain gauge in the clearing of an orchard or a grove of trees would
be a recommendation for a good site.
The height of the surrounding objects should not exceed twice
their distance from the rain gauge. If vegetation serves as a
windbreak, understand that growth will greatly change the con-
ditions of the site with the passage of time. What may originally
have been a good site may not always remain one.
Vegetation grows dramatically over time. Any construction
nearby that takes place after the installation may also make a
site undesirable by altering the wind currents and rainfall pat-
terns around the gauge. Under no circumstances should any
nearby object be allowed to grow above or hang directly over the
gauge.
The rain gauge is solidly built to withstand years of outside use;
however, vandals could ruin it. Always try to install the rain
gauge where it will be protected from vandalism.
Avoid installation in low places where runoff from heavy storms
could flood the gauge or wash it away. The rain gauge would not
be hurt by submersion, but it would be unable to measure.
Do not drop the rain gauge or expose it to shock; that could dam-
age the jeweled bearings.
1.5 Installation Installation of the rain gauge is simple. Just follow the procedure
listed below. Step 7 is optional depending on the requirements of
your particular installation.
1. Unpack the rain gauge from the shipping box. Save the box
and packing to return the rain gauge to Isco if that
becomes necessary. Remove the insert that holds the tip-
ping bucket. Remove the outer tube (white cover with fun-
nel) from the rain gauge by unsnapping the two latches on
the side.
2. Locate the bottom (mounting) plate of the rain gauge. This
is golden-colored metal. Mount this plate securely to a sta-

Model 674 Rain Gauge
Section 1 Operation Instructions
1-3
ble horizontal surface that is relatively level. Isco suggests
using corrosion-resistant hardware for mounting. The
mounting holes will accommodate hardware as large as ¼
inch in diameter.
3. This is very important: Level the rain gauge by adjusting
the three thumbscrews on the base until the bubble in the
bubble level is exactly centered.
4. Carefully remove the rubber band used to secure the tip-
ping bucket assembly. Do not apply pressure to the bucket
or the pivot arm. Do not attempt any adjustments.
5. Reinstall the protective outer tube on the rain gauge.
6. Route the cable from the rain gauge to the flow meter. Coil
any extra wire by the flow meter.
7. If necessary, you can increase the distance between the
flow meter and the rain gauge to 1,000 feet (maximum) by
splicing a two-wire #18 AWG cable (user- supplied)
between the Isco-provided cable and the rain gauge, as
described below.
Disconnect the Isco cable from the terminal block inside
the rain gauge and splice the user-supplied cable to that
end of the Isco cable. If the wiring and the splice will be
exposed to the weather, use wire appropriate for outdoor
use and insulate the splice properly. A weatherproof box
may be necessary. Do not cut the M/S connector from the
Isco cable unless you are connecting the rain gauge to
equipment that does not have a compatible connector. You
will not be able to reconnect it easily.
1.6 Maintenance The Isco Rain Gauge is built of quality materials to withstand
years of exposure to the elements. Normally, no maintenance is
required.
Once a year (or more often if conditions warrant) you may want
to remove the cover and check the gauge to see that it has not
been affected by the buildup of dust, debris, or insect infestation.
The rain gauge is factory-calibrated and needs no further adjust-
ment. If your installation is temporary and you intend to move
the rain gauge from site to site, use care in transporting the unit.
Again, you could damage the jewelled pivots for the tipping
bucket if you expose the rain gauge to a severe shock, such as by
dropping it. If you move the rain gauge frequently, always secure
the tipping bucket with a rubber band and use the original pack-
ing box to protect the unit during transport.
Repack the rain gauge as it was originally shipped to you if you
need to return it to Isco.

Model 674 Rain Gauge
Section 1 Operation Instructions
1-4
1.7 Electrical
Considerations
The electrical output from the Isco Rain Gauge is the rapid con-
tact closure of a normally open reed switch. The rain gauge is
not itself a powered device. It contains neither batteries nor
transformer and does not connect to the AC line. Electrically, it is
a “dry contact”switch, with power supplied from whatever device
it controls.
When you connect the rain gauge to an Isco Flow Meter, the cur-
rent through the switch contacts is very low and there is no prob-
lem with line losses or damage to the switch contacts. However, if
you plan to use the rain gauge for general-purpose rain measure-
ment with other types of equipment not specified by Isco, please
note the following:
CAUTION
The reed switch is rated for pilot duty only! The sealed con-
tacts are limited to 10 watts (or 10 VA), 200 VDC maximum.
Exceeding these limits may cause welding or rupturing of the
reed switch, ruining it. For safety considerations, Isco recom-
mends connection only to equipment supplying 30 volts or
less, AC or DC.
Be particularly careful using the rain gauge with equipment sup-
plying DC voltages at higher current loads or equipment present-
ing an inductive load to the reed switch. Never connect the rain
gauge directly to any equipment where enough current passes to
strike an arc when the contacts switch. You should always buffer
such equipment with a solid state switch (transistor, IC, SCR,
etc.) or a sensitive relay.

Model 674 Rain Gauge
Section 1 Operation Instructions
1-5
1.8 Technical
Specifications
The technical specifications for the 674 rain gauge are presented
in Table 1-1.
1.9 Replacement Parts
List
The following page contains a list of replacement parts for the
Isco 674 rain gauge. The illustration shows the location of the
numbered parts, which are described in the accompanying table.
Table 1-1 Technical Specifications for the 674 Rain Gauge
Type: Tipping bucket
Orifice: 8 inches (20 cm) diameter
Sensitivity: 0.01 inches (0.25 mm) or 0.1 mm (0.004 inches)
Accuracy: (Metric)
(English)
± 1½% at 5 cm/hr; +3.5, -9% up to 13 cm/hr
± 1% at 2 inches/hr; +3, -4% up to 5 inches/hr
Maximum Capacity: 22 inches/hr (38 cm/hr)
Connector Pinout: Pin A - Red, +12VDC from Flow Meter;
Pin D - Black, Output from Rain Gauge
Output Signal: Contact closure, 50 milliseconds minimum duration
Switch Type: Normally open; encaps. reed; 10 W 200 VDC, 0.5 A
Height and Diameter: 13 inches (33 cm); 9½ inches (24 cm) at base
Weight: 10 pounds (4.5 kg)
Operating Temperature: 32° to 140° F (0° to 60° C)
Storage Temperature: -40° to 140° F (-40° to 60° C)

Model 674 Rain Gauge
Section 1 Operation Instructions
1-6
Figure 1-1 Replacement Parts List Illustration
1
MODEL 674
RAIN GAUGE
2
3
3X
4
3X
5
6
7
2X
METRIC
VERSION
METRIC
VERSION
8
2X
9
10
11
12
12
ITEM INVENTORY NO. DESCRIPTION
603284003
603284004
603283012
603283016
209020400
603283006
201900000
410991001
603283004
233042800
603004149
MOUNTING PLATE ASSY
TIPPING BUCKET ASSY
MAGNET MOUNT
MOUNTING ROD
MAGNET .12 DIA ×3/8LONG
DRAIN SCREEN
SPRING LOADED VEE JEWEL BEARING
SENSOR MAG PRXTY.175/.800 SPST
LEVEL ADJUSTING KNOB
NYLON WASHER .253 ×.506 ×.01
CBL ASSY RAIN GAUGE 50'
8
9
603283023 INLET SCREEN MESH
603284010 TIPPING BUCKET ASSY METRIC
1
2
3
4
5
6
7
10
11
12

Before returning any instrument for repair, please call, fax, or e-mail the Isco service
department for instructions. Many problems can often be diagnosed and corrected over
the phone, or by e-mail, without returning the instrument to the factory.
Instruments needing factory repair should be packed carefully, preferably in the
original carton, and shipped to the attention of the service department. Small, non-
fragile items can be sent by insured parcel post. PLEASE BE SURE TO ENCLOSE A
NOTE EXPLAINING THE DEFECT.
Return instruments to: Isco, Inc. - Attention Repair Service
4700 Superior Street
Lincoln NE 68504 USA
Mailing address: Isco, Inc.
PO Box 82531
Lincoln NE 68501 USA
Phone: Repair service: [phone] (lab instruments)
[phone] (samplers & flowmeters)
Sales & General Information [phone] (USA & Canada)
Fax: [phone]
Email: serv[email protected]
One Year Limited Warranty *
Factory Service
Isco instruments covered by this warranty
have a one-year limited warranty covering
parts and labor.
Any instrument that fails during the warranty
period, due to faulty parts or workmanship,
will be repaired at the factory at no charge to
the customer. Isco's exclusive liability is
limited to repair or replacement of defective
instruments. Isco is not liable for
consequential damages.
Isco will pay surface transportation charges
both ways within the 48 contiguous United
States if the instrument proves to be defective
within 30 days of shipment. Throughout the
remainder of the warranty period, the
customer will pay to return the instrument to
Isco, and Isco will pay surface transportation
to return the repaired instrument to the
customer. Isco will not pay air freight or
customer's packing and crating charges.
The warranty for any instrument is the one in
effect on date of shipment. Warranty period
begins on the shipping date, unless Isco
agrees in writing to a different date.
Excluded from this warranty are normal
wear; expendable items such as charts,
ribbon, tubing, and glassware; and damage
due to corrosion, misuse, accident, or lack of
proper maintenance. This warranty does not
cover Isco on-line Process Analyzers and
certain Isco SFE instruments, which are
covered under different warranty terms, nor
does it cover products not sold under the Isco
trademark or for which any other warranty is
specifically stated in sales literature.
This warranty is expressly in lieu of all other
warranties and obligations and Isco
specifically disclaims any warranty of
merchantability or fitness for a particular
purpose. Any changes in this warranty must
be in writing and signed by a corporate
officer.
The warrantor is Isco, Inc. 4700 Superior,
Lincoln
,
NE 68504
,
U.S.A.
November 2000
•
#2217
* This warrant
y
a
pp
lies to USA customers. Customers in other countries should contact their Isco dealer for warrant
y
service.