This week we continue our suggestions for tower pump suction piping. In order to minimize problems with air, noise, and NPSH at the tower pump, Bell and Gossett recommends you try to keep high pressure drop devices out of the suction piping and also keep the velocity low. Let’s examine high pressure drop device this week.
Pump Suction Piping Rules – Cooling Tower Pumps and Piping – Part 6
Over the last several weeks we discussed the feared NPSH and showed it is rarely an issue at design conditions. More often than not, noise and pressure problems are caused by air in the suction piping system. The suction pipe, in many cooling pumping systems, is under very little pressure. In fact, the suction of the pump could be under a vacuum.
It’s all about Pressure – Cooling Tower Pumps and Piping – Part 5
Last week the R. L. Deppmann Monday Morning Minute gave an example of a pump selection for which we applied the margin multipliers to arrive at 24.5 feet of net positive suction head required or NPSHR. Now let’s turn our attention to the cooling tower pump suction piping and net positive suction head available or NPSHA. [Read more…]
It’s all about Pressure – Cooling Tower Pumps and Piping
Last week the R. L. Deppmann Monday Morning Minute left you with a multiplier of 1.3, 1.5, or 2.0 to use with the pump NPSHR. Let’s look at an example this week using the suction energy formula we introduced last week and add one more margin to the formula.
Where Cavitation Begins – Cooling Tower Pumps and Piping
Last week the R. L. Deppmann Monday Morning Minute defined NPSHR, and ended with the Hydraulic Institute (HI) definition as the absolute pressure that will cause the total head of the pump to be reduced by 3%, due to flow blockage from cavitation”. Of importance is the fact that it does not say that NPSHR is where cavitation begins.
It’s All About Terms! – Cooling Tower Pumps and Piping – Part 1
Most cooling tower designs and installations are commissioned without any issues. The few percent of times where problems arise will cause multiple meetings, emails, finger pointing, and added costs. The issues are not caused by bad luck or bad Karma; tower water pumping issues are typically caused by air, dirt, or improper application. [Read more…]
FAQs on Expansion and Compression Tanks – Part 2 of Series
Here we answer the questions:
Can I use a bladder tank and a steel compression tank in the same system? Adding on to my system, need to increase my compression tank/expansion tank capacity? How do I put another tank in parallel with the existing? Or my existing tank is too small, how do I increase capacity? What happens if the bladder type tank air charge is not increased to the proper fill pressure?
FAQs on Expansion and Compression Tanks – Part 1 of Series
Here we answer the questions:
How do I select a B&G bladder tank to replace my plain steel compression tank? What tank do I need for my XXX BTUH Boiler? Can I install the bladder / diaphragm tank on its side? How come the factory can’t charge my tank to something other than 12 PSIG? Why is my compression tank water logged? When I soap it, I can’t find a leak.
Compression Tank and Expansion Tank Selection Examples – Part 10
Today, let’s look at a couple of selections and how the tank sizes and costs may vary based on location and type of tank selected. Our examples are shown in figures A & B. In each case we will use a system volume of 1500 gallons of water with a supply temperature of 200°F and 20°F ΔT. The system is 60 feet high and in each case the maximum pressure is 50 PSIG.
Differences in Compression Tank and Expansion Tank Formula – Part 9
Now we understand the difference between expansion and compression tanks as described in the R. L. Deppmann Monday Morning Minutes of 1-9-12 and 1-16-12. What happens to the formula results when comparing these two types of tanks? In part 1 of this series, we introduced the formula for tank sizing. The denominator of the equation was: (Pa /Pf) – (Pa /Po)