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Lets give the following scenarios? a) 5 pumps = 100%, with 1 backup pump at 20%, what is the n value? b) 2 pumps and 2 backup (all equal size)= n+1 correct? c) 2 pumps and 1 backup (all equal size) Thanks

I looked through the forums and they get a lot into software. How do you manually calculate an expansion loop dimensions? Is there something in ASHRAE for this? An Example is 140 degree F water at 300 gpm in a 4" Black steel sch 40 pipe? Thanks

Do you now any coatings that could help?

I was told that it is C1045 turned, ground and polished. Does that mean that the shaft is corrosion resistant?

We have a large hanging hanger door with a large shaft that runs the length of the door. The motors are attached at the top and pull of the 3 pieces of the hanger door together using the pulley and wire system. What material do you think the shaft should be considering the site is about 1 mile...

Has anyone done a project on Plume Abatement for Cooling Towers? What is the best way of doing this? As of right now I don't have access to hot water at the site. Would I need to put a boiler on the site for this? Is there any other energy efficient way of doing this? Does anyone have any...

We have a shop where they teach people to work on automobiles. It uses a swamp cooler for cooling and they say it gets really warm in there. We are thinking of installing an air conditioning unit but are wondering if they would just fight each other since one humidifies and the other...

A lot of concern these days with energy usage in Data Centers. More and more people are looking at rooftop units instead of the CRAC units because of the economizer function. There is also the concern about bringing in outside particles and dirt that can damage the server equipment. What do...

So does anyone know the formula for room pressure in in w.c. as related to CFM in and out of a room? I read that entire thread and it did not make sense. The formula q=2610 gives some huge number. Thanks

A plan checker says I need a detail for fire and fire/smoke dampers, use the SMACNA "Fire Damper & Heat Stop Guide." I need this ASAP, could anyone help me out on this? I really don't feel like buying a book for a detail.

What do you like to use? I've read some articles that say balancing valves or AFLV (Automatic Flow limiting valves or Griswold) may not even be needed. My boss (30 year) veteran loves AFLV. But they use a lot of energy to maintain accuracy. I see now many manufacturers have pressure...

Anyone have any good articles or studies on variable condenser loops for cooling towers? Thank You

Lets say I have a gas regulator that regulates at 2psi, how far can this pipe go? Is there a loss/pipe length for natural gas?

I am little confused on how to size a gas pipe. I understand the length and BTU to get the size. But I don't get what chart to use. As I understand it, Low Pressure gas is <0.5psi and Medium is 0.5psi to 5 psi. If I want to run a medium pressure line from the meter and pressure regulator to...

I don't quite understand pumps. Lets say you have a Vertical Turbine Pump. The pump curve is what you will see basically at the outlet of the pump in terms of pressure and flowrate because there is basically no suction side friction loss. Lets say you have an inline pump that was designed for...

We have a situation where there is about 10 labs that use condenser water. One lab usues about half of the water requirements. We piped in a manifold system with a VFD pump to maintain a 50 psi pressure. Later they told us that every lab needs to have constant pressure (plus or minus 1-2...

You could always use CPVC Sch 80 if your worried about damage from things hitting it or high pressure. The labor is pretty much the same except the pipe is $2x PVC, which is still dirt cheap. I guess just dont freeze the water in the pipe and it will be okay. I couldnt find any specs on the...

Can anyone help me understand the difference in ferrous pipe types. Most piping for HVAC, commercial use black steel or ductile iron. What is the difference and what applications does each one suit best. Is black steel more resistant to corrosion? Is cast iron pipe still used? Are these the...

As a couple year engineer in the HVAC business, I would like to ask the veterans what books would you recommend that I get to help me better design and understand HVAC systems. I have several ASHRAE books,CRANE piping book, text books, which help in understanding the basics. What books do you...

I got two questions about this device: 1. When the piping system is drained, does the automatic air vent open up to let air into the system to allow the water to be drained? If the ball drops down when the water is drained, I would think it would let air in. 2. Does it only vent out air...