Leaky Blower Safety Relief Valves in Pneumatic Conveying Systems

Do you have money to burn?? Of course not, yet chances are that you are doing just that within your pneumatic conveying system.? Have you ever noticed the hissing sound of such valves when you tour your plant? If so, you are wasting electric energy and maybe risking future maintenance issues.? I cannot tell you how many cement and food processing facilities I have been to, where not at least some valves leaked severely.? You may think the cause is the valve itself. Think again:? Most likely it is your system that does not need all the air and hence is blowing it off through the valve.? The fix is not necessarily a new valve, but either a new belt drive or motor speed slow-down by means of a variable speed drive.

You do not need to be a blower expert to be able to troubleshoot this issue.? Ask your plant operators and production personnel if any product quality or process problems exist in the area you are reviewing.? Guess what, you can turn down the blower speed, if your valves blow off air from conveying (or aeration) systems that are working fine.?The problem assessment step is the most important one; you can leave it to your system OEM, or the blower manufacturer to help you figure out how much to turn down the speed.

Recently?I was invited to review a 75HP vacuum blower system that we were able to slow down by 20%.? Based on 24/7 operating service and the local electricity rate the customer was able to save over $7,000 per package – they had a total of 8 (!).? This is not only more money in your pocket, but it is also easier on the blowers and drives.  Besides of increasing the total service life, this measure also helps reduce the overall CO2 envelope of your plant – you can help the environment by using less energy.

Especially positive pressure relief valve create another issue in plant areas where blowers are installed in building or sound enclosures:? The hot air escaping the valves literally super heats the area around the blowers.? This tends to cause long term reliability issues as the hotter than normal blower intake air lets the machine run even hotter.? Lube oil viscosity decreases, which can cause premature bearing failures.? And it usually reduces the oil service life too (mineral oil in particular).? Elastomeric (rubber) blower shaft seals tend to harden, which can cause oil leaks:? Catastrophic failures follow quickly.? I am sure you get the idea, it is even more money in your company’s budget.

Ralf Weiser

2 thoughts on “Leaky Blower Safety Relief Valves in Pneumatic Conveying Systems”

  1. Dear Mr. Weiser

    Thank you very much for the friendly references…

    After so many experiences in the the field of valves,what is your real recommendation?…

    Best regards

  2. Dear Dr. Ergun,

    it is my intend to raise awareness that saving money in a pneumatic bulk conveying system may be as easy as listening to pressure relief valve blow off noise. If that is the case, investigate the leaks cause: Turn down the blower speed if no system or final product quality issues caused the PRV leak in the first place.

    Merry Chrsitmas,

    Ralf Weiser

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