Flow rates and pressure formula for gland water service.

[Ork1]

I am in the midst of commissioning a mill which will extract gold. Question is; where can I find a formula for gland water service on a 14" by 12" slurry pump which will feed slurry to the cyclone pack 3 levels up?

 

[Artisi]

Pressure will need to be slightly above the pressure at the stuffing box to ensure flow is sufficient to flush any product trying to enter the stuffing box and secondly to ensure cooling / lubrication of the packing, It can't be calculated as it is too variable and depends on the pump / stuffing box design. Both under pressure and over pressure create their own problems - both usually resulting in a short life for packing's and shaft sleeve life. As for flow rate, again depends on design. Best ask the pump manufacturer, they should have useful and available information.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[Ork1]

Thank You Artisi,
I know you have some mining experience, you are correct;slurries are variables, pressures fluctuate in addition, we are running a vfd which adds to the situation of "getting it right". I have 24GPM going into a 1 inch pipe to the stuffing box, there is, however, some concern as to the amount of water being added to the slurry process. It is Warman pump, tried , true and tested. We are, however, just running water in a loop for the commissioning, we just noticed some steam and probably some cavitation as there is a "witches hat" in the intake pipe(for construction debris.... this will be removed for normal service. We have set the flow rate per Warman.
Thanks again!!!

 

[Artisi]

Steam from where? Doesn't sound good. Best way is to back-off the gland for initial start-up and slowly adjust the gland until you have reasonable slow drip - however you also need to monitor the flow rate to ensure the stuffing box is being flushed back into the pump.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[LittleInch]

You need to be careful of those "witches hats". They're often not made of much and won't stand too much DP before breaking and depositing all the gunge straight into the pump it is supposed to be protecting. If you haven't got gauges monitoring the DP then do so before you turn it back on again, even if you manage to clean it out.

24 gpm sounds like quite a lot to me for a stuffing box flush, but it that's what the vendor says then go with it. I would try and get a reasonably high pressure supply ( higher than your max inlet pressure) turned down before your pump so that any changes in the inlet pressure don't really affect the flow.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way