liquid hammer

[floppy]

I have a blast chiller pack twin compressor running two blast chillers. It has a 90 meter pipe run and has sever liquid hammer it is running on eevs . Any idears on how to stop it as the movment on the pipe is fracturing it.

[US Iceman]

When does the liquid hammer occur? What precedes this event?

[floppy]

when units are running all the time

[US Iceman]

Which line?

Suction, liquid, or discharge?

[fowlie]

do you mean vibration from the valves pulsing on the liquid line

[cadwaladr]

is the piping clamped correctly and are there any eliminators fitted

[cadwaladr]

are the pipes clamped correctly are eliminators fitted to the system what pipes or pipe is noisey does it need a muffler in the system

[lowcool]

liquid line pipe sizing ? liquid line solenoid fitted near expansion point & not in plant room ? assuming that it is the liquid line.

[Yuri B.]

Floppy, you mean 90 m long is refrigrant - not glycol - line? If the refrigerant, and if the condenser is at the plant room, then, maybe, subcooling is too low, and the liquid flashes off in the too long line on its way to evaporator.
And could anyone share his knowledge on whether there are slow action solenoids? (and how slow are they closing/opening)

[Magoo]

Hi Floppy. with long liquid pipe runs you have to be very careful with pressure drop in liquid line, because with too high PD the liquid will start to flash off and cause the TEV to hunt wildly , hence pulse flow and pipe hammer. A check would be install a sight glass close to TEV. So re-calculate line losses and re-size pipeline. Alternatively add a sub-cooler and drop liquid temp to coils.
magoo

[gwapa]

Floppy
It normaly happen in liquind line when the solenide valve is located close to the evaporator and the liquid line is very long.
Once we solve the problem moving the solenoid valve close to the receiver tank. Of course the liquid remaining in the line (after you shut down) will produce a post-evaporation. If the system is not a critical one it could help.

[chillyblue]

you can reduce it's effect by fitting a vertical colum of pipe(near the end of the run), via a "T", this will give the effect of a hydraulic damper, also avoid the use of 90deg sr elbows, use drawn bends or 45deg lr bends to reduce shock.

CB