Recent content by tmartin125

ASHRAE and SNAME T&R 4-16 (2015) use a formula for sensible heat gain from equipment operated by electric motors as follows: q_em = 2545*(P/E_M)*F_UM*F_LM where q_em = heat equivalent of equipment operation, Btu/h P = motor power rating, hp E_M = motor efficiency, decimal fraction <1.0 F_UM =...

Sandcounter, I apologize as my question may not have been clear. I am not referring to any nozzle reduction on the pump body itself as it is understood those loses should be accounted for in the pump curve. I am referring to reductions made immediately upstream of the pump casing in order to...

I have reviewed a number of forum discussions and posted guidelines regarding pump selection and pump nozzle sizing, and most appear to indicate that pump nozzle sizing is solely a product of the pump manufacturer's design and need not be considered in the system design and/or calculations for...

A colleague of mine says ASHRAE duct design analysis cannot be relied upon for air velocities in excess of 12,000 fpm. As evidence he references ASHRAE's Friction Chart for Round Duct (See 21.8, Figure 9 in 2009 ASHRAE Handbook-Fundamentals) which only goes up to 12,000 fpm. Is it true that a...

Looks like Mark's Mechanical Engineers Handbook says open expansion tanks should be located at least 3 feet from the highest point radiator or main.

The expansion tank is connected to the pump suction in order to create a point of zero pressure, or at least near zero pressure. I thought there would be a requirement for the expansion tank to be a certain distance above the highest point of the system but haven't been able to find this...

I work for a marine engineering company and we use ASTM F708 as a pipe support standard for most of piping applications. Not sure if this is what you are asking because I didn't fully understand the question.

I am designing a closed loop cooling system for multiple consumers at varying heights above baseline. The system will include a vented (open top) expansion tank to account for fluid expansion due to temperature differentials. The bottom of the expansion tank will connect to the suction side of...

Looking for a standard or publication stating maximum inlet velocity recommendations/restrictions for heat exchangers or different varieties. I am designing a cooling water system where one of the consumers specifies 185 GPM and DN 50 connections to the heat exchanger. Inlet velocity is in...

Miya2014, why is it advisable to consider the difference in velocity head? Or what is gleaned by comparing the two?

Thank you all for your comments, they are most helpful.

In my situation the pump is a 3196 Goulds with discharge nozzle size of 1.5" compared with 3" for the discharge piping. Difference in velocity is significant, 36 fps compared with 10 fps. The velocity head is either 20.4 ft or 1.5 ft depending on which velocity is used.

Also, if the velocity head at the pump discharge nozzle is required for calculation of pump TDH, why isn't velocity head considered at the pump suction nozzle?

I need some direction on velocity head for calculation of centrifugal pump TDH. Is the velocity to be used that measured at the pump discharge nozzle or at the pipe connected to the nozzle (usually larger than the pump nozzle)? Isn't the velocity head at the pump nozzle included by the...

Thank you for your comments and analysis. This is a difficult problem... I don't have a dynamic simulator.. Will have to do this the hard way with excel :)