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Section 2
2.7 Flow Proportional Operation
2.7.1 Contact Closure Input
2.7.2 Pulse Input
Note: The Sampler receives the
pulse on Pin C of the Auxiliary
Receptacle. The sampler ground
(Pin B) must be connected to the
flow meter signal ground.
2.7.3 4–20 mA Input
Note: Older model 4–20 mA
interfaces require correct loop
polarity to work properly. The newer
generation interfaces are not
sensitive to loop polarity.
Page 20
Flow Proportional Operation
6. Make sure the power circuit is grounded and protected with a Ground
Fault Interrupter (GFI).
The 900 All Weather Refrigerator Sampler is equipped to receive a
momentary (minimum 25 millisecond) dry contact closure of 5 to 17 V dc from
an external flow meter to collect samples in proportion to the stream flow.
An optional interface unit is also available to accept a 4–20 mA or pulse
duration input (Cat. No. 2021). To interface with other flow meter output
signals, contact the manufacturer.
The sampler is capable of accumulating 1 to 9,999 contact closures. Each
contact closure output from a flow meter represents a specific flow volume.
Some flow meters have an adjustable output, i.e. one contact closure for
every 100, 500, 1,000, 10,000 gallons of flow, etc., while others have a fixed
output. In either case, the contact closure signal will be sent more frequently
for high flow rates, and less frequently for low flow rates. The sample
frequency will increase as the flow rate increases and likewise, will decrease
as the flow rate decreases, thus taking samples in proportion to flow rate.
To connect the sampler to a flow meter, use the Signal Cable
(Cat. No. 940 or 540). To connect to another brand of flow meter, use the
Open-Ended Signal Cable (Cat. No. 941 or 541). A contact closure input
corresponds to pins A and C on the Flow Meter/Auxiliary receptacle, and
signal cable connector. The signal cable wires are white and yellow
respectively. Polarity is not important unless the same closure signal is sent to
more than one sampler.
The sampler can accept a 5 to 12 V dc pulse input directly from a flow meter.
The sampler is capable of accumulating from 1 to 9,999 input pulses.
This can be used in the same way as the Contact Closure input to control
sample frequency. Use cable (Cat. No. 941) to connect the sampler to a V dc
pulse source.
An optional interface unit is available (Cat. No. 2021) which converts a
4–20 mA flow meter output into 12 V dc pulses (see
(100% flow rate), the interface sends ten pulses per minute; at 4 mA (0% flow
rate), the interface sends zero pulses.
The interface has a 3 ft cable with a connector on one end, and a 10 ft cable
with two open wire leads on the other. Insert the connector into the sampler
receptacle labeled "Auxiliary", located on the left side of the control housing.
On the 10 ft cable, the wire with clear insulation is positive (+) and the wire
with black insulation is negative (-).
Improper wiring may cause damage to the transmitter and receiver(s). Use a
multimeter to check the sampler interface for proper polarity if the sampler
does not respond to the 4–20 mA signal.Select the dc volt function on the
Figure
6). At 20 mA
8837hrd.fm
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