Acceleration Head in AODD Pumps
Acceleration Head in AODD Pumps
(OP)
Hi Folks.
I need your advise.
Does using (Inlet stabilizer / surge suppressor / tranquilizer / pulsation dampener) on the suction side of the pump reduces the calculated acceleration head? If Yes, can we quantify it by using any equation / formulae?
I need your advise.
Does using (Inlet stabilizer / surge suppressor / tranquilizer / pulsation dampener) on the suction side of the pump reduces the calculated acceleration head? If Yes, can we quantify it by using any equation / formulae?





RE: Acceleration Head in AODD Pumps
RE: Acceleration Head in AODD Pumps
Pls note a suction dampener will work well only if it it sized correctly (very often, believe it is not), and source vessel pressure is constant. It is better to reduce dependance on these devices as much as possible by selecting multiple head recip pumps (better than triplex at least) and/or using a NPSH booster pump. It is common occurence in industry that recip pumps lose capacity on volatile fluids application due this cause only.
RE: Acceleration Head in AODD Pumps
I have a very marginal difference between NPSHr Vs NPSHa after including the acceleration head loss.
NPSHr: 3m
NPSHa: 2.8m
After including Vapor pressure values as well.
That's why I am trying to see if Inlet stabilizer can reduce this acceleration head. If yes, how do we quantify it?
Hi georgeverghese
I am using a AODD Pump.
Can you please advise the HI std section you are referring to? Or the respective formula? Thank you
RE: Acceleration Head in AODD Pumps
Have not seen pulsation dampeners being used for these.
These pumps are said to be "more tolerant" of vapor in feed - pls check with the pump vendor if your approach is necessary / adequate. How much have you have tweaked your calcs to make it look like NPSHa > NPSHr ? What are you pumping here ? If you have no room for pulsations in the feed, try a Moyno pump or some other non pulsating rotary pump.
RE: Acceleration Head in AODD Pumps
RE: Acceleration Head in AODD Pumps
How much of that 3 ft NPSHR is acceleration head?
RE: Acceleration Head in AODD Pumps
RE: Acceleration Head in AODD Pumps
Other rotary non pulsating pumps would include gear and screw pumps.
RE: Acceleration Head in AODD Pumps
Hi georgeverghese,
Pumping fluid is petrol / Pumping temp: 90 degC / Vapor pressure: 0.7Bara @ 90degc
Capacity: 5LPM
the pipe length equivalent is 60m / 1".
NPSHr: 3.2m (Inc of NPSHr + Acceleration head + Vapor pressure @ temp)
NPSHa: 2.8m
Hi Dubmac,
This is a suction head condition. So I presume no issues with dry priming.
The issue is with the overall distance from suction tank to pump flange (60m) & velocity head.
The inlet stabilizer supplier assures that the acceleration head can be reduced to zero by increasing the capacity (Meaning: use 2" instead of 1"). Thereby, reducing the pressure spikes by >83%.
I am having difficulty in coming to a logical conclusion here.
Hi Moltenmetal,
Noted on your point. Thanks.
- How about we use an Expander after the first elbow from Min. straight suction run & match the pipe size with inlet stabilizer? In that way, the velocity head should be slightly reduced due to bigger line size & inlet stabilizer getting filled.
- Or I use 1" Inlet stabilizer for 1" line size.
Please share your thoughts. Thank you
RE: Acceleration Head in AODD Pumps
RE: Acceleration Head in AODD Pumps
Friction drop in 60m of say 22mm id pipe at 5 litres/min is low.
Raise the liquid height in source tank and / or decrease acceleration head loss.
RE: Acceleration Head in AODD Pumps
Thanks for your reply. The problem is that the system / piping cannot be changed. The pump needs to suit to this requirement.
Hi georgeverghese
May I know why is that the "A gas charged suction side pulsation dampener wont work if this tank is open to atmosphere". Since this was not informed by my Inlet stabilizer supplier. Moreover, this is a suction head.
RE: Acceleration Head in AODD Pumps
An empty chamber-type pulse dampener may still help you.
At the end of the day, does it matter? If you get some minor cavitation, you will lose some pump capacity. So what? Make the pump marginally larger. Petrol is a mixture without a single boiling point, so cavitation of petrol is much more gentle than it is for a pure component like water.
Why on earth is this "petrol" at 90 C? How often is it at 90 C- always, or is this a design condition that the unit will NEVER operate at? Cooling the suction line can help reduce the vapour pressure, if you really can't change the elevation head.
I'd be very worried about what happens when your AODD pump's diaphragm bursts and you introduce a large amount of compressed air into that 90 C petrol! The suction head would be the least of my worries frankly.
RE: Acceleration Head in AODD Pumps
So far I've not come across an empty chamber type pulsation dampener.
I am though not able to understand "if the suction pressure is BELOW atmospheric pressure". For a closed tank (Suction head) with no vent, the vapor pressure being high.
RE: Acceleration Head in AODD Pumps
The vapour pressure of your petrol is less than 1 atm at 90 C- it is not boiling inside the tank. Accordingly a pulsation dampener with a bladder/diaphragm in it which is pressurized to a pressure ABOVE atmospheric pressure, will hold the bladder/diaphragm against its suction limit stop- it will not vary in volume and act as a pulse dampener at all.
An empty chamber-type pulsation dampener is just like it sounds: it is a stand pipe- a capped piece of pipe connected to a tee, containing a bit of noncondensible vapour at start-up, and mounted as close as possible to the pump's suction. It has no diaphragm or bladder to separate the gas from the liquid. On each discharge stroke, it will fill completely with liquid, compressing the vapour in the headspace a bit. During the suction stroke, instead of drawing liquid from the tank through a long pipe with lots of frictional loss, the pump will draw down this standpipe a bit. It must be sized so that one stroke's worth of volume does not take the level in the standpipe below the NPSHR of the pump. You don't buy these- you make them out of pipe fittings. A small port at the top of the standpipe will permit it to be re-filled with nitrogen or another inert gas periodically, as the gas will eventually dissolve in the flowing liquid and leave the system Because your fluid has a substantial vapour pressure though, that's not such a big deal- it merely means you should make the standpipe a little taller so it can fill with vapour rather than requiring an inert gas fill.
RE: Acceleration Head in AODD Pumps
http://www.pulsationdampeners.net/aodd-pump-dampen...