Hello, I'm Jeff Hannan, Eastern District Manager for Engineered Systems and today
we're at the Gorman-Rupp facility in Mansfield, Ohio, actually in the
Engineered Systems demonstration area, where today we're going to be looking at
our priming tower, which is one of the units that we have that we can run through
some different scenarios from field applications and do some troubleshooting.
Basically what we have for setup is we have a T3 pump, a 3-inch
Super T-Series pump by Gorman-Rupp mounted about 15 feet above an open tank of water.
We've got a suction line that's got glass piping and we've got some blue
colored water, so we can see the suction line is full right now.
Also on the suction side, we've removed the suction flat valve, so we've got a straight-end suction.
There are no check valves on the suction side to hold the water.
Then on the discharge side, our piping has no discharge check valve and no plug valve
in the discharge line. We removed a section of pipe and installed a fire hose,
so that we can see how violently or quickly the water fills that hose when
we're looking at the different types of starters that we're using today.
Then our discharge line comes back down to the tank and I've got three different areas
that I can pump the water. I can let the water recirculate back to the tank.
I can pump the water through the wall to a separate holding area, so I can lower the
level in the tank. Then I've also got a discharge line that allows me to
discharge directly onto the suction inlet of our suction line.
We're using a 15 horsepower motor with our pump, and we're running at about 1650 rpm
pump speed for most of the demonstration.
The first scenario we want to look at is
using the across the line starter to run the pump. Again, this is going to be a
full on and a full off situation, so what I want to do is from the control panel
here, I'm just going to run through a couple of cycles of start and stop,
and we're gonna keep our eye on that discharge hose and see how quickly
the fire hose fills with water and with a certain amount of violence, or force,
that it does fill that line. Again, this is a three-inch pump with a
15 horsepower motor, not a large amount of horsepower or a large amount of flow
that we're talking about, and you see how much water hammer or shock that we can
put into the system here. So we'll run through a couple of cycles.
But again, if you're in a situation where you're pumping water up a high hill or
in a high head application, probably been in a pump station where you're pushing
the water up the hill, you shut the pump off, the water starts rushing back to the
pump station, check valve start slamming, header piping starts moving around, and
again this is only a 15 horsepower application that we're looking at right here.
There's no control with an across line starter. It's full on, full off.
You take what you get and sometimes that causes a lot of issues with header
piping and check valve slamming and things of that nature.
What we'll do now is I'll switch over to the soft starter, or the reduced voltage
solid-state starter in the middle here, and this one now allows us to have some
ramp time on the start and on the stop. We'll do the same scenario.
We will run through a couple of cycles here and we're going to again watch the fire hose
and just see what kind of force we're looking at. This should slow that down
quite a bit and fill the hose a little bit slower.
We'll run through a couple of cycles now to demonstrate that.
You can hear the pump starting to ramp up
and then bring it back down as it ramps back down.
Go through another cycle
Just by adding this soft starter, we've eliminated a lot of that violence, a lot
of that hammer action in the fire hose. That's a nice thing about the soft
starter, too. You can see physically it's about the same size as you cross the
line starter, so it doesn't take up that much additional panel space.
Costs have come down on those to make them a nice option for pump stations.
If you are in a situation where water hammer could be an issue, or you want to control the
starting and stopping of the flow of the liquid in the discharge,
that can be a nice option for you.
The last one that we want to look at now is of course the
variable frequency drive, and again, this is going to give you more of an
infinite control. There are only limits on the start time and the stop time on the
soft starter, but again, it basically runs at full voltage when it's up to speed.
The variable frequency drive can run at any speed between 0 and 60 Hz
that you want it to operate. On this one, we've got it set up for a
little bit slower ramp time even than the soft starter. Again, we'll watch
the fire hose just to give you an idea of how much control we can have over the
flow of the liquid
Now I'll hit the stop and bring it back down to off position.
I'm going to ramp it back down much slower than even the soft starter did before
Then one more time on the start just to see how slowly it does fill the fire hose.
Then bring it back down on the stop
Many times, the variable frequency drive is used to control flow, or to match wet
well levels in a sewage wet well, but in certain cases it may be necessary to use
the variable frequency drive where we have high head applications or situations
where water hammer is present at a pump station and we want to have more control
over the liquid as it leaves the pump station.
You can see from looking at the three different types of starters. Again, an across the
line starter is gonna be full on, full off, no real control over the flow.
The soft starter, the reduced voltage solid-state starter, again gives you a
on-ramp and an off-ramp that can help control a little bit with water hammer.
Then the variable frequency drive, which gives you the most control going
from 0 Hz to 60 Hz, or from stop to full speed.
That concludes this portion of our demonstration today.
For more information on pump hydraulics, equipment, or application engineering,
watch Gorman-Rupp's YouTube channel, and visit us at GRPumps.com