Do calculate conveying air velocities carefully before you make any changes. In a suck-blow, or push/pull system, where you draw material into the pipeline under vacuum and deliver the material under pressure, you would typically have a 5 inch bore pipeline for the vacuum section and a 4 inch bore pipeline for the positive pressure pipeline, and you would have almost the same pick-up velocity in both pipelines. The free air flow rate, or the air mass flow rate, is the same for each. This is due to the compressibility of the air. In fact, for a given power input to the air mover you are likely to get the same material flow rate through the 5 inch vacuum line as you are through the 4 inch positive pressure conveying line.

Have a look at my article on "A Performance Comparison of Vacuum and Positive Pressure Conveying Systems" published in Bulk Solids Handling, Vol 26, No 1, 2006. ■

Dear crawlejg,

Changing a vacuum system into a pressure system is already discussed in your earlier question.

Then, the blower could handle 11”HG.

Ask your supplier for a hose that can withstand that working pressure.

The hose must be anti-static (corn starch). better is steel.

success ■

A spiral steel re-inforced rubber hose with a pressure rating of at least 30 psig can be used for this test. These hoses are widely available from most conveying system vendors. Hose should be grounded from end-to-end to prevent accumulation of static charge.

Regards,

Amrit Agarwal

Consulting Engineer

Pneumatic Conveying Consulting

Email: polypcc@aol.com

Ph and Fax: 304 346 5125 ■

If you are conveying downhill, please see our website.

http://sciroccohose.com/index.html ■