#2 TM Transmitters

Description

The differential pressure transmitter reads the high and low pressure signals from the dP producing meter and turns that reading into a 4-20mA signal that can be read as flow or dP directly or transmitted to a PLC or SCADA system. That signal can be linear to the differential pressure, but more commonly is linear to flow by using the square root extraction in the transmitter. DP transmitters are highly accurate devices that can read differential pressures as low as 0.1”wc. They are ideally mounted as close to the dP producing meter as possible, but can be mounted further away as required. For dirty fluid applications or highly viscous fluids the use of seals and capillaries is required to prevent plugging of the lines.

There are various options for materials, indicators, electrical certifications, etc. They are also generally used with a 3-valve or 5-valve manifold that helps when performing set up operations like zeroing and can also make removal of the transmitter easier should it have to be replaced or worked on.

Multi variable transmitters can be used to compensate for changes in line temperatures and pressures generally associated with gas flow applications. This requires the use of an RTD mounted to the dP producing meter to measure and send the temperature to the transmitter.