How to Check the Suction Pressure of a Dust Collector

Dust collection inside industrial facilities keeps breathing healthy.

Dust collectors are widely used in nearly every industry to remove harmful airborne dust contaminants. Like vacuum cleaners, they consist of two major sections: collection and separation. One of the processes used for separation is multi-stage filtration, which can remove a range of dust particle sizes. The most common method of checking filtration systems is comparing suction pressure before and after the filtration section. A U-tube manometer can be used for this check.

Things You'll Need

• Portable U-tube manometer, inches of water measure
• Tubing to connect the U-tube manometer to dust collector, 1/4-inch inner diameter, 1/2-inch outer diameter (or check manometer instructions)
• Calculator

Instructions

1. 

   A well-used U-tube manometer needing a rescue.

   Connect the ends of U-tube manometer to the dust collector. You may need to drill 7/16-inch-diameter holes--one in the entrance plenum just before the filter, and one just after the filter. Smooth the holes with emery cloth after drilling. Some units already come with plugged holes for aftermarket instrumentation.

2. Push the ends of the tubing about 2 inches into the two holes. The slightly smaller holes should provide a smooth, snug fit.

3. 

   Sometimes precision pressure switches can sense too much suction loss to signal an alert.

   Clean the dust collector's pre-filter and main-filter, or purchase and install new ones. Start the dust collector. The level in one side of the U-tube manometer will go up and the other side down. The suction side will be higher.

4. 

   A vacuum cleaner without enough suction is similar to a clogged dust collector.

   Add the two readings in inches to obtain differential pressure across the filter. For example, if the upper leg reads 2 inches and the lower leg 2 inches, the total differential across the filter is 4 inches. Compare the readings with the specifications in the dust filter's user manual for your specific unit. Most units are designed for normal running with 1 inch to 6 inches of differential across the filter. With any higher differential (lower suction pressure), flow through the unit will be too low, and the filter should be visibly checked for cleaning or replacement.

5. Disconnect the tube in front of the filter. The manometer will go higher up than before.

6. Add the measurement of the two legs of the manometer again. This is the basic suction pressure of the dust collector's suction motor, behind the filtering, which you can also compare to the manufacturer's specification to see if any attention to this motor itself is necessary.

7. Reconnect the tube in front of the filter and disconnect the tube behind the filter. This is the suction pressure available to pull air into the front of the unit. This might be a very low pressure, in the range of 1 inch of water column. The manufacturer will also have a specification for this parameter. A leak in the collector housing could also cause this suction pressure to be too low.

Tips & Warnings

• Monitor the manometer regularly to determine dust collector performance.

• The manometer can be made portable to use on a number of collectors.

• The manometer can be used on any kind of blower or suction device, or industrial vacuum cleaner with suction up to 60 inches of water column pressure.

• Do not intake manometer fluid when filling the tube.

References

• BPA Industry Experts and Comparisons: Media Filtration in Dust Collectors
• Flex-Kleen Division/Met-Pro Corp: High Pressure, High Vacuum Pulse-Jet Dust Collector /Principles of Operation
• Air Cleaning Technology: Industrial Air Cleaners

Resources

• Measurement of Pressure with the Manometer