Pressure tank installation
Pressure tank installation
(OP)
Hello,
I have the following situtation regarding the installation of a water pressure tank and I would like some advice:
I have a well with a submersible pump, pumping water to two 1000 gls storage tanks adjacent to the well site. About 1100 feet away from here there is going to be a shed with a pressure tank to supply water to a few surrounding facilities. I am a little confused about what to do to feed this pressure tank. I could install a pump besides the storage tanks but the problem is it is quite far to send the signal from the pressure switch at the pressure tank to the pump at the well site. Then again I could put the pressure switch at the pump outlet at the well site, with the pressure setting for the pressure tank plus the friction losses in the 1100 ft pipe. I am not sure however is that is going to work allright. Any suggestions or comments are most welcome.
Thank you,
I have the following situtation regarding the installation of a water pressure tank and I would like some advice:
I have a well with a submersible pump, pumping water to two 1000 gls storage tanks adjacent to the well site. About 1100 feet away from here there is going to be a shed with a pressure tank to supply water to a few surrounding facilities. I am a little confused about what to do to feed this pressure tank. I could install a pump besides the storage tanks but the problem is it is quite far to send the signal from the pressure switch at the pressure tank to the pump at the well site. Then again I could put the pressure switch at the pump outlet at the well site, with the pressure setting for the pressure tank plus the friction losses in the 1100 ft pipe. I am not sure however is that is going to work allright. Any suggestions or comments are most welcome.
Thank you,





RE: Pressure tank installation
The pressure switch at the pump at the tanks, will probably work fine. Thing is it may not be overly accurate, but a 10PSI difference from some desired pressure at the pressure tank likely will make little difference anyway.
Remember that the pressure switch at the tanks with the pump will see, (as you've mentioned), a higher pressure than the pressure tank would see,(only when the pump is running). When the pressure switch sees the cut off pressure and stops the pump the pressure will step drop quickly to the pressure tank pressure without the pumping loss(static pressure). If your pressure switch has too little hysteresis, and your pumping line too much resistance, then the this delta change will get you. But if you make the interposing line large enough so the dynamic pressure change is reasonable, and use a switch with separately adjustable on-off settings you will be fine.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Pressure tank installation
RE: Pressure tank installation
RE: Pressure tank installation
Itsmoked aswering your question, the storage and pressure tanks are pretty much level, being the latter seated maybe 3 ft higher.
Valvecrazy, the cycle stop valve sounds good to me, and for my pumping capacity (around 30 gpm) not very expensive. Altough I did not understand what is the use of the 1 Gal pressure tank. Perhaps I did not explain myself well:
On the well site I have a submersible well pump feeding two atmospheric 1000 gals storage tanks; this pump will start/stop responding to low/high level signals from the tanks; just beside these tanks will be another pump, with a pressure switch, which will pump water to the pressure tank located 1000+ feet away.
RE: Pressure tank installation
If there is electricity at the pressure tank/s You could use a radio transmitter between the pump and the pressure tanks. There are a lot of fairly inexpensive units that can essentially pass a switch contact wirelessly. It could cost less than the valve and (local to the pump) small pressure tank solution Valvecrazy has sagely suggested. It gets you essentially what you want. No wires and pressure tank feedback.
Example: First one I saw on a search. Many others may be better. Just showing what I mean.
http:/
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Pressure tank installation
Otherwise you need to use something like the radio control that itsmoked suggested, to send a signal from the remote pressure tank to a relay at the pump.
RE: Pressure tank installation
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Pressure tank installation
http://www.cyclestopvalves.com/applications_1.html
However, you can still install the 1 gallon tank as shown in this picture and install a larger tank anywhere downstream.
You could install a submersible in the storage tank or a jet pump outside the storage tank. Either way the set up would be pump, CSV, tee with pressure tank and pressure switch off to the side, and other side of tee goes directly to distribution line. The CSV will make the pump start and stop at 1 GPM, which with a tank of any size attached to the pressure switch, will eliminate the chattering of the switch. Once the pump is running, the CSV will vary the flow to exactly match the usage by maintaining a constant pressure. IE; with 40/60 switch, the 50 PSI CSV will maintain 50 PSI as long as between 1 and 30 GPM is being used. When all water outlets are closed, the CSV will fill the tank from 50 to 60 PSI at a 1 GPM rate. Then the switch shuts the pump off at 60 PSI.
Filling the tank at 1 GPM is why the remote tank will fill at the same rate as the tank at the switch, because there is no friction loss at 1 GPM. Starting and stopping the pump at 1 GPM is what keeps the switch from chattering, because there is no water hammer or transients. Varying the flow to match the usage is why a tank as small as 20 gallons size, with only 5 gallons of draw down, is all that is needed.
RE: Pressure tank installation
Steve Wagner
RE: Pressure tank installation
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Pressure tank installation
The valve and small tank control eliminates the transients and the need for any time delay. The demand is first met by the water from the little pressure tank. This gets the water moving down line before the pump starts. Then the pump starts at 1 GPM against the valve, and the flow makes a smooth transition from the being supplied by the little tank to being supplied by the pump.
On shut down, the demand must stop completely. Then the pressure tank is topped off at 1 GPM before the pump shuts off. No destructive transients, no need for time delay.
RE: Pressure tank installation
With that low 1 GPM flowrate to the pressure tank, am I not going to have my transfer pump running almost constantly?
RE: Pressure tank installation
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Pressure tank installation
Pumps are made to run. They will last longer if they run continuously than if they cycle off and on, any way you do it. Ideally, every demand should be set for 30 GPM, so the pump runs continuously anytime there is a demand. With the CSV, as long as the demand is more than the ½ to 1.5 GPM (depending on the particular pump) the pump will run continuously instead of cycling.
The counter intuitive part, is that the amperage or power consumption of most pumps will decrease in proportion to the flow rate. In most cases there is little if any difference between the power consumed by a pump that is throttled with a valve, compared to reducing the RPM with a drive. In other words, even though the pump may run continuously, the power use is proportional to the flow required.
Not only will the continuous running increase the life of the pump system but, it virtually eliminates transient pressure waves, as they mostly happen from starting and stopping the pump.
When there is no demand or less than the valves minimum flow, the tank will fill and the pump will shut off.
As described earlier, when the pump does start or stop, the 1 GPM minimum through the valve in conjunction with a small pressure tank, also eliminates transients which will bounce the pressure switch as well as cause other problems.
RE: Pressure tank installation
When considering minimum flow, you must account for internal recirculation, radial and axial loads imposed on the pump shaft which leads to higher bearing loads, deflection of mechanical seal faces, and in some cases shaft failure etc etc.
Also, I am in complete disagreement with you on the blanket statement that "They will last longer if they run continuously than if they cycle off and on, ........"
A pump that is operating below its recommended minimum flow is slowly destroying itself and will suffer a lot more damage and give a lot more trouble than a correctly sized unit which is cycling within the limits of its design.
RE: Pressure tank installation
RE: Pressure tank installation
Then you are probably talking about "toys" within the pump industry who's shaft size is usually oversized for the hydraulic duty, resulting from the need to be able to assemble with ease and not having to have the skills of a watchmaker.
So back to your blanket statement - what is your recommendation for a 3000kW boiler feed pump minimum flow, or a 2000 kW axial flow cooling water pump.
RE: Pressure tank installation
"the shaft slenderness is not an issue and is usually far more than adequate for the normal range of operation within the acceptable hydraulic range for which they are designed."
Acceptable hydraulic range for which they are designed means the shaft and bearings are made to minimal standards. A nickel more worth of shaft and an extra dollar on the bearings and radial deflection would not be an issue. Heavy duty bearings and a stronger shaft would make the pump last longer, and I believe that is the major reason most pump manufacturers don't do it.
Anyway this thread is about a 30 GPM pump moving cool fresh water. That pump can be throttled back to as little as 1 GPM, and can run that way continuously without damage.
RE: Pressure tank installation
Regarding shaft design, I must say that the pump companies I have worked for over many years do not/did not design pump shafts to the bare minimum - which happens to cover pumps from a few kW upto many thousands of kW.
RE: Pressure tank installation
RE: Pressure tank installation
This is generally the case. Since a strong shaft and heavy duty bearings can prevent radial deflection, there is usually no problem with throttling most pumps. While pump companies will say it is OK to run their pumps at complete dead head for 60 seconds or less, very few have even tested their pumps at minimum flow for extended time periods. Therefore, I tested them myself. I tested a 50 HP submersible by running it continuously at 5 GPM for 12 months. I tested 200 HP and 250 HP vertical turbines running continuously at 5 GPM for months. I tested 100 HP and smaller end suction centrifugal pumps as low as 3 GPM. I tested residential size jet pumps and submersibles running continuous at ½ and 1 GPM for many years. After the tests, these pumps and motors where disassembled and inspected for damage. Absolutely no damage was found on any of these pumps or motors. There were no signs of radial deflection, bearing or shaft damage, heat buildup, or cavitation like wear from recirculation. In the last 15 years there have been several hundred thousand systems installed with these type valves. To this date we have yet to see a single pump destroyed by low flow rates. I believe low flow is something that has not been tried, because most people falsely believe throttling will destroy a pump. This is definitely not the case when moving fairly cool water.
"Apparently Cycle Stop Valve is a brand name, is there a generic name for this type of valve or is this a patent protected sole source valve?"
Constant Pressure Pump Control Valve is a generic term. However, the patented internal bypass of the CSV is the key to valve reaction speed and dependability. There are several other valve companies trying to copy the CSV but, valves with drilled holes or bypass tubes have many problems and do not give the same performance as a CSV.