{"id":3942,"date":"2025-12-17T14:11:49","date_gmt":"2025-12-17T20:11:49","guid":{"rendered":"https:\/\/scadametrics.com\/blog\/?p=3942"},"modified":"2025-12-21T10:52:41","modified_gmt":"2025-12-21T16:52:41","slug":"differential-pressure-meters-visual-display-and-scada-totalization","status":"publish","type":"post","link":"https:\/\/scadametrics.com\/blog\/?p=3942","title":{"rendered":"Differential Pressure Flow Meters – Visual Display and SCADA Totalization"},"content":{"rendered":"
\"James

James Mimlitz \u2014 ‘Slim’ @ SCADAmetrics<\/p><\/div>\n\n\n\n

Differential Pressure Meters<\/strong> are a class of no-moving-part flow meter whose principle of operation is based upon the Venturi Effect<\/strong><\/a>.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

These meters are typically outfitted with a transmitter, which produces a 4-20mA signal, which is linearly proportional to rate-of-flow (gpm, lpm, etc…).<\/p>\n\n\n\n

However, in many instances, it is also desirable to ascertain totalized flow (gallons, cubic feet, cubic meters, etc…). This can be accomplished by programming a connected PLC to perform a time-integral of the rate-of-flow signal (Remember calculus?!).<\/p>\n\n\n\n

SCADAmetrics offers a hardware-based solution that does not require a PLC programmer, nor a PLC; and it is based upon two devices: The SCADAmetrics model MTP Milliamp-to-Pulse Converter<\/a><\/strong>, and the model APK.PLUS Analog\/Pulse Kit<\/a><\/strong>.<\/p>\n\n\n\n

The MTP Converter<\/strong> accepts a 4-20mA signal from the Flow Meter transmitter, and converts into a 0-20 Hz pulse output, which can then be totalized by the connected APK.PLUS<\/strong>.<\/p>\n\n\n\n

As an example at the extremes, during periods of ZERO flow, no pulses are transmitted by the MTP. During periods of MAXIMUM flow, a 20 Hz pulse is transmitted by the MTP (20 pulses per second, or 1200 pulses per minute). Therefore, the pulse\/gallon ratio can be calculated by dividing [MAX_GPM] by [1200]:<\/p>\n\n\n\n

Example: 4-20 mA : 0-20 Hz :<\/strong> 0-300 gpm<\/strong>
…
300 gal\/min \/ 1200 pulses\/min
300 gal = 1200 pulses
1 gallon = 4 pulses
1 pulse = 0.25 gallon<\/strong><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

The APK.PLUS<\/strong> can be special-ordered to support a customized gallon\/pulse ratio, and the customized ratio is activated by setting dip switches [9,10,11,12] = [on,on,on,on].<\/p>\n\n\n\n

When ordering an APK.PLUS for this application, please make sure to specify the 20mA flow rate (gpm, lpm,…).<\/p>\n\n\n\n

\n\n\n\n

The following diagram illustrates the instrumentation hookup (click to zoom):<\/p>\n\n\n\n

\"\"<\/a><\/figure>\n\n\n\n

The APK.PLUS provides the user with a sequential display of the following:<\/p>\n\n\n\n