What is Differential Pressure and How Is It Measured?

Anytime that air is moved through filters, there is resistance. Measuring the resistance is important on a dust collection system because it's an indicator of filter effectiveness and filter cleaning performance. The difference in pressure between the clean side of the filters and the dirty side of the filters is referred to as differential pressure, which is measured in inches of water column. Differential pressure should be monitored on all types of dust collection systems, including pulse-jet baghouses, reverse air baghouses, cartridge dust collectors, and mist and wet-type collectors.

It's important that the differential pressure gauge is connected properly and the tubing is without kinks or blockage, which could distort the true reading. When connecting the gauge, the low pressure port is connected to the clean air plenum. The high pressure port is connected to the dirty air plenum, commonly with a static pressure tee to stabilize the readings and reduce the chance of dust migrating to the gauge.

The differential pressure readings should be monitored and recorded for each dust collection system. If the dust collector is operating and the differential pressure sensor is at zero, it's an indication of a leak and that airflow is passing through the dust collector without being filtered. When new filters are installed, the reading is at its lowest effective point. As material builds up on the filters, the differential pressure increases. The cleaning system cleans the filters, which keeps the differential pressure in the working zone. When the differential pressure sensor reads higher than the working zone and cannot be reduced to acceptable levels by the cleaning system, the filters are at the end of their useful life.

The differential pressure can also be used to control the cleaning system. This is effective at reducing compressed air consumption and extending filter life. A pressure switch is used to start the cleaning system at the high point and continue cleaning the filters until the differential pressure gauge level falls below the low setpoint, where it shuts off the cleaning cycle. This prevents the filters from being over-cleaned and wasting compressed air. If your dust collector's cleaning system does not need to run continuously, we recommend using the differential pressure sensor to control the cleaning.

Have more questions about differential pressure and how it's measured? Contact AM Industrial today!