PM8 Purge Module

---

Key features

• Purge pressure up to 6 bar (87 PSI)
• Flexible trigger options: Manual, digital, RS232, RS485, CAN
• Sensor protection by automatic pressure relieve

---

About the PM8 Purge Module

In many pressure measurement applications it is necessary to clean the pressure ports from dust or blockage.

The PM8 Purge Module is designed to be connected between sensors and pressure taps and makes it possible to apply purge pressure to the measurement openings.

The internal valves are controlled by a micro-controller. When a purge operation is triggered, first the sensors are disconnected from the pressure taps. After that, the internal high pressure valve is activated and routes the purge pressure to the taps.

To avoid a pressure kickback into the sensors in case of a permanent blockage of the measurement line, the high pressure valve is closed and the purge pressure is relieved before the sensors are reconnected to the measurement lines. This protects the sensors from overpressure due to a possible purge pressure kickback.

Operation Modes

In normal operation (A), the pressure that is to be measured (on the left side of the figures) is routed directly to the sensor. When the purge mode gets triggered, the sensor is disconnected from the pressure port first (B). After 100ms the purge valve connects the purge pressure to the measurement tap and with that air gets blown out, cleaning the measurement line. At the end of the purge operation the purge pressure gets disconnected and the remaining pressure in the measurement line is relieved (D). 

This is an important feature to protect the sensor from overpressure which can occur when the measurement line is permanently blocked and the purge pressure can’t escape through the measurement opening.

After the pressure relieve phase the sensor is reconnected to the measurement line again (A).

---