Pressure transducers

Micro-Comm pressure transducers come in four standard pressure ranges with two configurations. The standard ranges are 0-15 psi, 0-60 psi, 0-100 psi and 0-300 psi. The configurations are weighted snub nose (suspended in liquid) and those with ¼ inch NPT thread, usually connected to the source with white polyflow tubing. Other transducers supplied by Micro-Comm include well drawdown transducers, consult your operation manual for more information.

Erratic readings from transducers are often caused by clogging because of debris in the sense line or in the holes of the weighted snub nose. Flushing out the unit usually will clear the obstruction. For transducers connected with polyflow tubing, disconnect the tubing from the transducer and allow water to flow until is it unobstructed. If possible, remove the ¼ inch fitting in the end of the transducer to flush out the inside- be careful, the stainless steel diaphragm inside the transducer can be easily damaged. Do not attempt to scrape out and debris, use running water only.

When removing and reinstalling the ¼ inch fitting on the transducer, do not over tighten; it may crack the transducer housing. Avoid using brass fittings in transducers if at all possible.

It is recommended flushing of transducers at least once per year to help insure reliable operation.

Replacement transducers may be shipped with or without cable attached. If cable is attached, simply pull it through the conduit, cut to length and land wires on the terminals as they were previously connected.

If the transducer was shipped without cable, you may watch the video here http://www.micro-comm-inc.com/Micro-Comm/support/transducer-replace.html for easy instructions.

Testing of transducers can be done with a voltmeter that reads DC milliamps. With zero psi pressure input, the transducer will output 4 milliamps. At the max rated pressure (example 100 psi) the transducer will output 20 milliamps. Any reading between 4 and 20 is algebraically equivalent to the psi range (example 0 to 100 psi). For example, 12 milliamps would equal 50 psi.

To test output of a pressure transducer:

1. Set voltmeter to read DC milliamps

2. Remove red wire (+) at PLC.

3. Connect black voltmeter lead to red wire

4. Connect red meter lead to the terminal where the red wire was previously connected.

5. Read value on the voltmeter. Remember, at zero PSI you should read 4 milliamps. 3.95 or 4.05 or in that range is acceptable. At the full PSI rating of the transducer (i.e., 100 psi) you will read 20 milliamps.

6. If there is pressure on the transducer and you know that value, you can measure the milliamps and per above, algebraically calculate to see if the transducer is putting out the correct amount of current for the pressure applied. NOTE- if comparing to a pressure gauge, note that many gauges are accurate only to within 5 or 10 percent, and comparing the gauge reading to the transducer will seem off. Remember that a working transducer is MUCH more accurate that an analog gauge, even those that are high quality.

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