Re: hydraulic flow meter needed

Posted by NCWayne on October 30, 2012 at 08:08:59 from (69.40.232.132):

In Reply to: hydraulic flow meter needed posted by bill in colo on October 29, 2012 at 20:43:05:

As you have found aout already a basic meter is going to be expensive. There are some out there cheaper, but they typically aren't going to be rated for the pressure like your needing. Unfortunately even at places like Northern Tool (see link below) they are in the $300 to $400 range, and that is about the most basic, pressure rated meter you can buy. Looks like their's is made by Webtek so it is a quality, name brand tool that is worth the cost. I've got one on my service truck that I've had for nearly 12 years and it always works when I need it to.

Now, the problem with a meter like that is that it has no way to put a load on the system. In many cases a pump will show an acceptable flow rate at low pressure but will drop off as the pressure gets higher. I had one the other week on a skid steer doing just that. The flow was like 20 GPM but it slowly dropped off as pressure rose and by 1000 psi it was at zero. If I had not loaded the system it would have appeared like the pump was OK resulting in a bad diagnosis, and alot of headaches looking for another problem that didn't exist. Anyway, in order to load the system like I did you also need to get a high pressure needle valve and install it on the outlet from the meter. With the valve in place you can slowly close it and apply a load to the system. ----------WARNING HERE-------With this setup you have to physically insure that you don't close the valve to far and dead head the pump. Doing so can cause a sever over pressurization of the system resulting in damage to components or lines rupturing.---------

If the need for a rupture disc is there, and when checking variable displacement pumps it is a very good thing to have, then you are going to need a different style meter. Below is a link to Webtek's site and one of the meters similar to the other one I've got that has a disc. The reason I say a rupture disc is needed with variable displacement piston pump is that it's possible for the pump to be acting up and for you to close the load valve down too far and causing a pressure spike if the pump reacts and starts putting out more flow. I was checking the pump on an excavator once when that happened to me. The swash plate was sticking (the problem) causing the pump to not respond like it should. I had closed the load valve nearly shut trying to build pressure and couldn't because of the low flow from the pump. Just shy of completely closed on the load valve the pump decided to respond and went to full stroke. This resulted in about 45 GPM trying to go through what would amount to a pin hole so the resulting prssure spike would have been huge had it not been allowed to bypass the meter by blowing through a 6000 psi rupture disc.

Ultimately you may find a decent used meter, but it will still probably not be as cheap as your wanting. Even then, without the accessories like a load valve,(and they aren't cheap either) the meter alone won't do you any good.

Good luck.

• Northern Tool flow meter

• Webtek

Replies:

• Re: hydraulic flow meter needed bill in colo 08:43:23 10/30/12 (0)

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