What is Legionella and Why Should You Care?

Legionella. It is a potentially fatal bacterium that for the most part has managed to fly under the radar of the general public since it was first determined as the cause of Legionnaires’ disease in the 1970s. Despite the fact that there are well-known techniques to prevent the growth of the causative bacteria, legionellosis (commonly known as Legionnaires’ disease) has taken the lives of well over 100,000 people in the U.S. alone. Furthermore, reported cases of the bacteria has risen 217 percent in just the last decade, according to the Centers for Disease Control and Prevention.
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“What Pressure Do I Pre-charge My Hydropneumatic Tank To?”

 In our last blog we talked about how to properly size a hydropneumatic tank – but the engineer’s work doesn’t end there.  He or she also needs to specify the appropriate pre-charge on the drawings.  Otherwise the tank will not be set properly at start-up and will not provide the intended energy savings.
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How To Size A Hydropneumatic Tank in A Pressure Booster System

 Properly sized hydropneumatic tanks are a non-negotiable element in a domestic water pressure booster system--including variable speed systems.  Without a hydropneumatic tank, pumps will short cycle on and off during no flow periods.  Even a leaky faucet can cause pumps to operate unnecessarily without this pressurized reserve of water.    
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ASME Hydropneumatic Tanks Play An Important Role in Pressure Booster Systems

 “Do I really need a hydro-pneumatic tank on my variable speed pressure booster?”

 It’s a question many engineers will ask, particularly after ASHRAE 90.1 – 2010 takes effect in commercial building codes as early as October of this year.  As we discussed in an earlier blog on variable speed pressure boosting, the new ASHRAE standard no longer permits pressure reducing devices to reduce the pressure of water supplied by booster system pumps.  This essentially puts an end to constant speed pressure boosting, which brings variable speed to the forefront.  But since the whole point of variable speed pumping is to more accurately align demand with supply, why would hydro-pneumatic tank still be required?

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