It’s all about Pressure – Cooling Tower Pumps and Piping – Part 5

Norm Hall Monday Morning Minutes

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…]

Where Cavitation Begins – Cooling Tower Pumps and Piping

Norm Hall Monday Morning Minutes

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. [Read more…]

It’s All About Terms! – Cooling Tower Pumps and Piping – Part 1

Norm Hall Monday Morning Minutes

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…]

Max Pressure of Expansion and Compression Tanks (Cont) – Part 6

Norm Hall Monday Morning Minutes

[Continuation from last week’s MMM] Let’s assume we have a SIX story health care building and the heating system is 90 feet high with a 180 degree supply temperature. The pump and boilers are on the first floor. The BRYAN boilers selected come with 125 PSIG relief valves. Let’s also assume that the pump has a capacity of 800 GPM at 100 feet at design. [Read more…]

Maximum Pressure of Expansion and Compression Tanks – Part 5

Norm Hall Monday Morning Minutes

Maximum pressure in a hydronic system depends on a number of variables. Last week we used an example to introduce the maximum pressure at the expansion tank. Let’s look at a couple more examples. EXAMPLE TWO: Figure 1 shows a one line diagram of a heating system with a boiler and pumping system. [Read more…]