I have an aboveground storage tank holding glycol that I have flowing through a centrifugal pump to various outlets (totes, drums, other tanks, etc.)
There’s a number of manual ball valves both before and after the pump that all could be switched out for a better option.
Even though the pump itself is controlled to stop by a flowmeter feedback, since it is above ground tank, I currently need to manually shut a valve to prevent continued gravity flow through the pump after it shuts down. My current thinking is to put an electric actuator on my downstream valve that ties to the pump controller to shut when the pump is not running.
My question is is that the simplest/best option? Is there another specific type of valve for this type of function (to stop a gravity feed when the pump i not spinning?) I’m trying to look around, but with these types of things it always seems like if I just have the right keyword to look for (correct valve terminology), a whole slew of better options comes up.
How accurate do the charges need to be? We use a ball valve with a rotary turn actuator, positioner, and two limit switches (1 is a spare). We call it a “dribble valve”. The majority of the charge flows with the ball valve wide open, then it closes to about 5% open for 1-2 minutes. When the charge gets to the pre-act quantity, because of drainage, the pump stops and valve closes. With a little bit of work, it can be highly accurate.
“My current thinking is to put an electric actuator on my downstream valve that ties to the pump controller to shut when the pump is not running.”
Where is this valve located? i presume it is located at tank outlet to keep fluid contained at the tank in the event of associated problems, i.e. leaks, etc.
It doesn’t need to be terribly accurate. I just want something so the operator doesn’t need to stand there waiting for the automated pump to switch off just so they can close a valve by hand. We’re talking 1000’s of gallons metered, not mL of metering. The material also has a fairly large acceptable range too, so there is a decent amount of tolerance in this process. I’m eyeing something very simple at the moment:
The valve I was thinking to put it on is after the pump. I’d rather not tie the tank outlet to the pump controls because I can easily see an instance where I need to get material out of the tank and bypass this system entirely.
It comes from the tank, to the pump, then goes either through a heater or can bypass the heater by isolating it with valves 3 and 5. The flowmeter is before the final valve (7) and feeds back to the pump motor controller.
I was planning on putting the actuator on valve 7 because that is the outlet anytime the pump is engaged. There are also camlock connections at the tank outlet, pump inlet, and after valve 7.
I’d rather not put it on tank outlet valve because that valve is left closed unless the tank is in use, so it is better protected against leakage this way I think. It would also have less wear without the constant use on that valve.
Have you considered a programmable meter with an automatic shut-off.
Many years ago, I worked on a concrete batch plant. The water volume was fairly critical.
We used a flow meter with an automatic shut-off. The gallons needed was set and the meter counted down to zero. With about 5 gallons left, the valve cut the flow down to a minimum. When the count reached zero, the valve closed completely and the pump motor was shut off.
That’s pretty much what I’m doing. The pump is controlled to shut off from the meter feedback already. What I’m trying to do is make it so the operator doesn’t have to manually work valves at the start/stop of the pump to prevent gravity flow from the tank through the pump even when it is not running.
If Valve 7 is automated and Valve 1 is still to be closed manually, which sounds like it might, but I’m not sure, won’t the operator still have to “stand there waiting for the automated pump to switch off”?
Be aware you may be building a thermal expansion scenario for the piping system between two closed valves, especially with a heater in line.
No they wouldn’t need to standby if just one valve is closed automatically. Again, this is simply to meter out the glycol to another storage container or blend tank. The issue is that once the correct amount is metered, the pump shuts off, but flow will continue from gravity which then overshoots the metered amount if a valve isn’t closed. So if valves 1, 2, or 7 are closed at the same time as the pump cutoff, all flow would be halted once the pump shuts off, and prevents the tank contents from continued flow by gravity and makes the metered amount inputted by the operator.
I think I am explaining the process poorly. I’m not sure how to do it better though. Let me write a scenario below that explains all the valve positions and maybe that will help.
I don’t have much of any concerns about spills or leakage from that tank. The equipment and tank are all in good shape (inspected about 2 weeks ago actually) and has an abundance of secondary containment in the event of a problem.
The heat/expansion issues should be fine too. The heater is automated and it is only meant to maintain the tank contents at a “warm” temperature of 50°F - 80°F while circulating.
Assume all valves start closed. Let’s say I want to meter out 1000 gallons of glycol to another tank and I want to pass it through the heater.
I would open valves, 1, 2, 3, and 7, while keeping 4, 5, and 6 closed.
(Valve 5 in this scenario is my “control valve” because it it physically located within arms reach of my pump controller. So it is closed at the moment.)
I input 1000 gallons into my pump controller.
I press start on the pump controller and I manually open valve 5 at the same time.
At the end of the 1000 gallons the pump automatically shuts off and I manually shut valve 5 simultaneously (However I could shut 1, 2, 5, or 7 to get the same effect, it is just that 5 is the easiest to access)
The controller now measured my 1000 gallons and I have that 1000 gallons in my destination tank without any measuring by the operator.
My goal is to eliminate the manual operation of that valve, so the operator can essentially plug in their volume, walk away, and the volume is transferred when they come back.
The meter that I mentioned had the shut off valve built into the meter, as well as a limit switch to stop the pump.
By the way, it was completely mechanical. The only electrics was the limit switch to stop the motor.
The meter kept the setting so it did not have to be set for a volume each time it was used for a similar batch.
The controller will save 10 preset batch volumes has has an additional relay for a valve. Yeah, I wish I had thought of this before ordering the pump and meter because I would’ve gotten something that had a built in valve.
Once they were finished using it, they would likely close all the valves if there wasn’t anymore material needed. They might set it to recirculate the tank contents through the heater if the bulk temperature needed to be increased for a batch later in the day.
