Water Pressure Tank Bladder Diagnosis FAQs #2

Questions & Answers on Internal-bladder Water Tanks

Can We Eliminate the Water Pressure Tank Completely Q&A

Can I run my pump without a pressure tank?

I have a gravity fed pressure tank pump. Can I run it without the tank? On 2020-09-13 by Dave Weston

by (mod) - certain water pumps (but not all models) don't need an external pressure tank

There are pumps that will run without a pressure tank as you can find in this article series.

Watch out: However if yours is a conventional water pump you can not use it without a pressure tank or it will experience severe short cycling which ultimately will destroy the pump

See GRUNDFOS SCALA 2 PUMP GUIDE

Can the water pressure tank be adjusted to get water to higher building floors?

I have a water pressure issue with my upstairs bathroom. can the pressure tank be adjusted to fix this problem - Alysa 11/11/12

Reply: no, the problem is elsewhere - probably the pump or pressure control switch or piping

No Alisa,

The water tank smooths the delivery water pressure but does not increase nor decrease it.\

Big Difference in Pressure Between Tank Air Valve and Water Pressure Gauge Readings

I reset Amtrol tank to 39 psi, now the pump shuts off at 41

Hi- just repressurised my Amtrol water tank to 39 psi (water pump shut off at 41 psi).

However, the Schrader valve at the top of the tank reads 39 psi, but the pressure gauge at the bottom on the actual water line reads 31 psi. Why the big discrepancy? and we're still having some problems with our water pressure on the second floor (new system- only three years old). - Paul 2/5/12

Reply:

Paul the pressure control switch on a water system is not lab grade equipment; the pressure gauges won't agree precisely, and an independent pressure measuring device l ike the one in my photo can help you understand what's going on,

but you can be darn sure that the pressure is the same at both points on a water system if measured at the same time.

Don't trust that pressure gage on your water tank or at the water pump to be spot-on.

Sometimes a gauge gets sticky and stops reading accurately due to debris clogging.

But a 7 psi difference between measuring air pressure at the tank top valve and water pressure at the pump gauge says that one of those measuring devices is a bit far off.

Fortunately the gauge itself is not a control device; it's just telling you what pressure it sees where its mounted.

If you trust your tire gauge reading at the Schrader valve, replace the low-reading tank pressure gauge.

Water pressure is too low right before the pump kicks in

Right before my well pump is about to kick in (40 psi) if I have two items running (say shower and laundry) the water pressure is very low to the fixture further away from the tank. Example, someone is taking a shower on the second floor and I start laundry on the first floor.

The water pressure to the shower will drop to a trickle but the laundry is ok. This only happens right before the pump is about to kick in. It seems like the pump cannot recharge the tank quick enough. If I do this while the tank is at 60 psi, it is ok. This tank was replaced a few years ago with the same size that was originally there and with the exception of this one issue, it seems to be fine. - Maxx 3/7/2013

Reply: diagnose debris clogged pressure switch and clarify water flow vs pressure

Maxx,

It's possible that your water pressure switch is debris-clogged so is slow to respond to a drop in building water pressure, letting water pressure fall below the CUT-IN setting originally made at that control. The solution for that is to replace the switch and also to clean or repalce the tube that conducts water pressure to the switch.

Background:

Almost everybody mixes up these points because the normal way we talk is about "water pressure" when what we really are talking about is water flow rate. Check for a pressure control switch not responding to a fall in water pressure - e.g. due to debris clogging at the switch.

Water pressure is measured as a static number when no water is flowing - say 40 psi or 50 psi in the whole system - when the pump has cut off (or is about to cut on at some lowe rpressure).

Water flow rate measured in gallons per minute is what we experience as "water pressure" in the shower - I guess because at a faster flow rate we get pressed-on harder by the water as it strikes us.

When we have poor "pressure" (water flow rate) at a fixture the problem is usually because of clogged pipes.

You can be sure this is true if the pump is capable of reaching say 40 or 50 psi of cut-off pressure. A second cause of poor water flow rate may be a very slow water delivery rate from the well - maybe because of a well flow rate restriction.

I figure if it were really the pump itself then the pump wouldn't reach cutoff pressure even if the well had plenty of water in it. Other problems like a leak in well piping also foul up delivered water pressure.

Take a look at

• WATER PRESSURE MEASUREMENT
• WATER PRESSURE PROBLEM DIAGNOSIS TABLE
• WATER PRESSURE DIAGNOSIS for WELLS

What is causing abnormally high air pressure in our water pressure tank?

Hope you can help me. I have a 16 y/o WELL-X-TROL WX 250 water well tank in my basement.

I just had a plumber come over and change out the pressure switch 40/60 The plumber drained the system , checked the air pressure in the tank which he found to be at 60psi. He then lowered it to about 34 psi (tank empty), changed the switch made sure everything was ok and when he left it was.

A day or two later my well started short cycling and the gauge would jump low then high to cut off at 60psi I kept an eye on it and called back the plumber to have him check it again. He rechecked and told my husband he raised the pressure inside the tank but on the ticket that was turned in, it was lowered.

It was okay for a day and started short cycling again. I then took out the water filter and found it to be clogged with sludge

I guess from the plumber draining the tank. I then cleaned it out and put it back in and tank was okay for a short while, the started short cycling again .

( UNIT SHORT CYCLES AS SOON AS I TURN WATER ON)

Today, 3/14/2013. 2 plumbers came back and told me my tank needs to be replaced but they drained it and found that the pressure in the tank was up at 60psi Again. What does this mean?. Now that they have left, the water ,pressure switch and tank seem to be okay. What do you think could be wrong ?

They want to put a new Well Mate tank in. What is the difference and first of all, AND DO I REALLY NEED ONE NOW THAT MY TANK SEEMS TO BE OKAY? THEY TOLD ME THAT THE GAUGE SHOULD READ AT 30 PSI ON AN EMPTY TANK. MINE WAS READING ZERO. IS THIS NORMAL???

...

My problem is that more air gets into the tank on it's own. I have drained tank, checked pressure and with each draining, the pressure at empty rises Is there a leak in the bladder which would allow air to come in after I have drained and reduced air pressure in the tank? Thank you.

- K.F. Kerhnonksen, NY 3/16/2013

Reply: difference beween high water pressure at a water tank and high air pressure in the tank

K.F.

"air is entering the tank on its own" ? Not really. Air comes from somewhere, for a reason that needs to be addressed. But I agree that you're on to something and that a proper diagnosis and repair of the problem have not been done.

If a water tank bladder has burst and thus leaks, nothing keeps water and air separated.

Air in the tank might enter the water supply, but especially on an internal-bladder type water tank where there is no air volume control used to keep putting air into the system, there is not NORMALLY any source of additional air entering the system. The tank becomes waterlogged and the pump short cycles.

However there can be other sources of air entering the system that are not normal, including:

1. an old snifter valve in the well or on the well piping that should have been removed when the new bladder type tank was installed
2. well water running low, pump picking up air
3. leak in well piping lets water out and air in depending on when in pump cycle

"Air pressure" in the water pressure tank at 60 psi is VERY HIGH, ABNORMAL, and should have raised a question (if it was really air pressure) of how it got there. Just bleeding out air doesn't fix anything if the cause is not found and fixed.

Now above I explain how we might get excess air entering the water supply system.

Details about that problem are at AIR DISCHARGE at FAUCETS, FIXTURES.

But I suspect your system is not accurately described, and that our answer lies in your observation that the pump was short cycling.

If the well pump is short cycling the most common cause is a waterlogged pressure tank - that is a tank without enough air or with no air at all inside the tank. The pump turns on, there is no air to compress, the pump therefore almost immediately reaches cut-off pressure and cuts off. Water is flowing, pressure drops in moments, pump cuts back on.

So you are describing a waterlogged pressure tank.

Details about diagnosis and repair are at WATER PUMP SHORT CYCLING.

In sum, I think it would be unusual (but not impossible) to have excessive air in the water system AND well pump short cycling. I imagine that might come up if you had an unusually signficant high volume and rate of air entering the system - say from an old air volume makeup device that should not be there, or a leak in well piping.

Keep us posted, what we learn will help others.

Abnormally high pressures in the water tank forced us to shut off the system - cause?

I replaced a 36 Gal Water tank in my home yesterday. Upon turning on the water and electricity to the pump, which was pre-pressurized at 25psi the pressure in the tank kept rising until I shut it off at around 70psi.

Each time I turned the water and electricity on the pressure would continually rise until a point where I would shut the power to the pump off completely to avoid over pressurizing the tank. Do you have any idea on what could be the problem? Thanks! - B.E. 7/23/13

Reply:

A competent onsite inspection by an expert usually finds additional clues that would permit a more accurate, complete, and authoritative answer than we can give by email alone. You will find additional depth and detail in articles at our website. That said I offer these comments:

Watch out: First, you were wise to SHUT OFF the pump - as overpressurizing the system is dangerous, risking a burst tank or piping. It is evident that the pump is working and water is entering the pressure tank, as its pressure climbs.

Second, I suspect that either a pressure is not connected, not working, or the pressure control switch may be mis-wired or defective. If you replaced some system parts but left an old pressure control switch it's possible that its sensor port is debris clogged. If so I'd replace the switch and its mounting or pressure sensing tube.

Fix Too-Small Water Draw-Down Quantity Before the Pump Turns On

I have a 18Lt pressuretank and SquareD switch. On installation it was all set to factory -switch 30psi -50psi and tank at 28psi. Not being happy with the low pressure at 30 I decided to turn the large nut clockwise until I got high pressure at 60.

Since doing this i notice the draw down has been reduced and causing the pump to cycle even with a half toilet flush. It used to last atleast 2 flushes before.

My question is, would this be because I didn't add pressure to the tank bladder? Should I do as above and add pressure to 38psi (cut in 40) and will this fix the problem?
Cheers from Australia! D Adam

Reply: set air charge properly including empty tank and 2 psi below CUT-IN

Adam,

See

WATER PRESSURE CONTROL SWITCH ADJUSTMENTS

there you will see the explanation of the large and small adjustment nuts in that control, and you'll see additional detailed articles about adjusting the two nuts individually and together; I suspect your switch needs corrective adjustments.

Keep in mind that if the air charge was not set with the water tank empty, it is incorrect. So that could also be the problem.

Reader follow-up:

I think you may have misunderstood my questions. Setting the adjustment nuts is fine as I've read nearly all the articles including the one you mentioned :)
What I'm trying to figure out is ...

1. Now I have my switch set to 40-60psi do I need to add air to my pressure tank to make it 38psi?

2. And is this why the draw down is less (because I increased switch cut in to 40 but didn't adjust the bladder/tank pressure?)

Reply:

Yes D. Adam; you want the starting pressure in the bladder tank to be about 2 psi below the cut-in pressure. Details are in an article titled WATER TANK BLADDER PRESSURE ADJUSTMENT - found by searching InspectApedia

When you change from 30/50 to 40/60 you still have the same 20 psi difference between cut in and cut out; Shifting to a 10 psi higher operating range but keeping the same delta or variable (20 psi) means that the higher pressure will push water out of the tank faster than before, reducing the *perceived* drawdown even more than the actual measured volume of drawdown.

In a table in the article above using a similar tank size, the pressure range change you make drops the drawdown volume from 6.2 to 5.4 g

But yes do set the tank air pressure as discussed in the article I cited, or generally at 2 psi below the cut-in pressure. That will give the maximum available volume and thus drawdown.

Reader follow-up:

Thanks Dan!
That basically answered my question. I'll adjust the pre charge over the weekend and see how it goes...hopefully no dramas (can't see a relief valve anywhere-only the fill in schrader, fingers crossed it don't blow up)
Cheers, D. Adam

Reply:

Great D. Sorry to be obtuse but often when communicating just by text it can be a challenge to get a clear idea of what's going on from the questioner's side.

As long as you stay well below the tank rated burst pressure you're safe. Certainly an air loading causing pre-pressurizing of a water tank at a pressure that is below the tank's operating range and below the cut-out pressure should be safe.

With smaller vessels, like a bicycle tire, it is easier to blow the thing up when hooking to a high pressure air source. But I did learn of a case in which a plumber was working leaning over a pressure tank connected to a submersible well pump - the pump was running ( and is capable of high pressure) - and blew the tank. He was working alone, was cut by the damaged tank, and died. Rare, but possible.

The common place to add a relief valve is on the tank tee at the bottom of the pressure tank.

What is the effect of increasing the air pre-charge pressure in the water pressure tank?

What happens if we increase the precharge pressure of water tank? will the water pressure increase also? just a newbie here. thanks (Apr 8, 2014) reese

Reply:

Reese, you are asking an important question as I know it's easy to be confused about this pressure and tank business.

Overall the pressure of water delivered at a plumbing fixture will never be higher than the pressure that can be produced by the water pump itself. The system pressure will vary while you are running water, between the pump pressure control switch cut-in and cut-out pressures, say 20-40 or 30-50 psi.

The pressure tank, containing air and water, is acting as a sort of spring to smooth the flow of delivery of water. If we didn't have that spring, then when the pump turned on it would quickly reach the cut-off pressure - in seconds - and cut off, then pressure would fall to the cut-in pressure - in seconds - and the pump would turn on. That rapid short-cycling of the pump will kill it as well as drive you crazy seeing water squirting at the faucet.

The pressure in the water pressure tank should be set to about 2 psi below the "cut-in" pressure of the water pump.

If you made the big mistake of setting the pre-charge pressure in the water tank to ABOVE the cut-in pressure of the switch, the effects is you are reducing the available water volume in the tank, tending towards a short-cycling system. Why? because at the higher pre-charge pressure the volume of the tank's air charge is increased when water has been pushed out of the tank.

If we take this to an extreme and fill the water pressure tank with air, in a bladderless tank no water will enter the tank and in fact air will be pushed out and into the building piping. In an internal bladder type tank, filling the tank with air, if it doesn't burst the bladder, eliminates any available volume in the tank for water - the pump will still turn on and off based on building water piping pressure and it will short cycle like mad.

If this is still unclear, ask me again.

Reader follow-up:

thank you for your important reply. in this case, how will i increase the water pressure to satisfy required pressure to supply 3 fixtures at the same time (shower, water closet, lavatory)in case we used them at the same time considering that this 3 fixtures are also existing in other rooms?

Our local water service is a bit weak. we have decided to buy a water storage tank with a capacity of 2000 liters, a 2hp jet pump with complete attachments (gauge, pressure switch, check valve), and a bladder type pressure tank (tank volume 33gal).

Pipe size is 1 inch in diameter from storage tank to pump to pressure tank. but after the pressure tank, the pipe size is only half inch in diameter all the way up to our rooms. I

compared the pressure of our local water utility and pressure from the pressure tank (without connecting yet to the building pipes), based on the squirt, water from the pressure tank squirts farther than the local water but when connected to the building they produce the same result (same water pressure output)its like that the pressure tank is useless.

Hope you can help me solve my problem. again thank you very much. (Apr 9, 2014) reese

Reply:

Typically people improve water pressure by one or a combination of measures. First we need to accurately diagnose the cause of poor water pressure - so that we can then choose the right repair.
Therefore, start at

WATER PRESSURE PROBLEM DIAGNOSIS TABLE

When the pressure tank is installed and filled for the first time where does the already in the tank air go?

When installing a replacement tank, when the empty tank is filled for the first time where does the air in the area being filled with water go? Does it compress or is there some kind of valve that allows the air to escape and be replaced with water? (May 5, 2014) Dan

Reply:

Dan thanks for the question.

The air doesn't go anywhere - that is, it's not supposed to escape or go away. Rather, it is being compressed. It's that compressed air that pushes water back out of the tank when you open a faucet, and it's that "spring" like feature of squashed air that pushes back that keeps your well pump from otherwise cycling on and off too rapidly.

With a New pressure tank, having trouble getting pump to turn off

I put a new pressure tank in--simer pre-set at 38#-----put a new pressure switch on pump--pre-set at 30-50#---I dropped the pressure in the tank (very carefully measured) to 28#----now having devil of time with pump even cutting in/off---have not made adjustment to switch yet-- must start pump manually ---

question-- read that on this site to let pump run until it shuts off observing pressure at which this happens-- will this burst the bladder with 28# still in tank?
thanks June 15, 2014) dave ross

I have a fairly new Well - X - Troll system that pulls water from the lake to feed my irrigation system.The pressure switch is a 20- 40 PSI switch. The pressure gets to 40 PSI fine and stops. However, almost as quickly as the irrigation system starts, the pump kicks in.

It goes down to about 30 lbs. pressure and stays there. Consequently the pump never stops and then eventually kicks the 15 amp breaker off. It's a 1 horse motor. Any idea on the problem? Need a bigger motor - new pressure switch so it drops to 20 lbs before it kicks in - create more zones in the irrigation system so it doesn't draw so much water at any one time - 20 amp breaker? (June 18, 2014) Pete

My tank keeps kicking on and off. In addition to this the it is making a loud thumping sound and water is squirting out of a ball valve... The pressure reading is sitting at a constant 40psi (supposed to be 60/40). And i have a Amtrol Champion series tank. Any ideas? (June 21, 2014) Rich

Reply:

Dave

A good diagnostic is at

WATER PUMP WONT STOP RUNNING 

Pete I suspect two conditions:

The water flow rate of the irrigation system exceeds the pump capacity ( or,a pickup screen is partly clogged), so the pump runs continuously at its maximum output which never gets ahead of the use rate, so it never shuts off until you turn off the water.

And there may be a problem with the pump itself, or low voltage, or voltage drop along a very long wire, that can also overheat the motor.

You could try running irrigation at a slower flow rate or in fewer zones at any time.

Rich: You want to see WATER PUMP SHORT CYCLING

Water system works ok only at low demand - we lose pressure at high demand

I have a submersed pump w/ a 30 gallon pressure tank, and a 40/60 pressure switch.39 psi in tank. At low demand, the system works normally. at high demand, the pressure continues to fall past the 40 psi cut in pressure and shuts off the pump, To restart I have to activate the bypass lever on the pressure switch and hold until proper pressure is established. (July 13, 2014) Anonymous (Feb 22, 2013)

The water tank precharge pressure is 1.94 bar but pump cutin pressure is 3bar - shall i increase precharge pressure?

Reply:

Anon
It's possible that the high water usage rate exceeds the well flow rate. In that case the switch is shutting off the pump to protect it from damage, working as it should.

Forcing the pump to run may damage it.

Try waiting an hour or more before turning on the pump after it has shut down. That gives the well time to recover. If the system runs normally at that point we have diagnosed the trouble.

Depending on the well's recovery rate it could take longer still for this procedure to work.

Trouble getting tank bladder pressure settings - is it a bad pump?

Recently replaced a 40 year old 20 gal pressure tank & its piping with a new Water Worker HT20B, 20 gal tank and new SS piping. Also replaced the old Square D pressure switch with new Square D 30-50 unit.

The first day, with the wrong pressure in the bladder (38psi) and some water hammer in the system, I bled the bladder down to 28 psi and it seemed to run OK for a time.

Then, strange things began to happen; the pressure switch would cut in at the normal 30 psi, however it seemed the downhole well pump wouldn't respond for a few seconds, then when it kicked in, the system pressure was already below the precharge of the bladder, so there was water hammer again.

Adjusted the bladder charge down to 25 psi, and again it seemed to run OK, but then the same phenomenon occurred. The pump didn't seem to start running for some time delay after the pressure switch "cut in". I did measure the voltage on the load side of the pressure switch, and it was OK, so I know that voltage was getting to the pump, however I didn't have the necessary instruments with me to see if it was actually pulling current immediately, or only after this "time delay".

The pump itself is also 40+ years old, however since this is a seasonal use cabin in MT, it actually hasn't seen much service. Nevertheless, does it sound as though the pump itself is failing? (Aug 16, 2014) John

Reply:

John you were on the right track but when "...[you] bled the bladder down to 28 psi and it seemed to run OK for a time. "
That 28 PSI should be the air pre-charge when the tank is empty of water.

Followup by John

Thanks Daniel, I should have clarified that statement - I did bleed the bladder down to 28 psi after draining the system and tank, and opening the system to atmospheric pressure. Guess I'm looking for some guidance on whether there could be a problem with the new surface equipment I installed (pressure tank, tank tee, check valve, pressure relief valve, pressure switch), or if it's downhole.

If it's downhole, I'm going to go ahead replace the entire assembly (pump, piping, wiring, etc.) as it's all 40 years old, and I don't want to have to pull it again in the future.

Reply by (mod):

John

Do you think that the delay in apparent response of the in-well submersible pump that occurs after the pressure switch has called for water could be

- a problem in a separate pump relay operated by the pressure switch? Some higher HP submersibles use a heavy duty relay control that is itself switched by the pressure switch.

- a leak in well piping that is draining back into the well? (Look for air discharge at fixtures)

About the old pump motor - that's a fair question to ask, but I'm not sure where to go with it. Look at not voltage but current draw to see if the pump is behaving as if binding or sticking (high current) or pumping air (low current). It'd help if you knew the pump specs which perhaps are not known.

What are the right booster pump station tank pressure settings?

I have a booster pump station including 4 pumps that they cut-in via pressure and flow rate. The pumps have VSD. The cutin level is 45m head and the pumps have to maintain the pressure at 50m head. I have got two 80L Pressure Vessels (29l drawdown volume of each)on the discharge line.

I want to know at what pressure should I charge the vessel (43 m or 48 or ?) ? another control on this station is that the PLC looks both at Pressure and minimum Flowrate (Aug 18, 2014) Vahid

Reply:

Vahid, In general the air pre-charge pressure in the pressure tank is set 2 psi below the cut-in pressure set at the pump controller. But your system merits comment by an engineer who has expertise in its special function and design.

Water pump and tank to support water source heat pumps - hissing noise - air in the water?

I use my water pump and water holding tank exclusively to support my water source heat pumps. The plumbing of the water tank is standard with a pressure switch controlling the power to the pump but the water discharges to a pond in my backyard after going through the heat pumps to pull the heat/cold from those units.

I also have a relay (tied to the thermostats of the water source heat pumps) wired in series to the water pump pressure switch to control power to the water pump so the it won't activate unless the heat pumps are in use.

The system has been in use for about 34 years and worked fine until recently. My problem now is that at times (but not all the time) there is a loud hissing sound like air mixing with water near where the pipe from the water tank ties into the water line heading to the heat pumps.

Even with the hissing sound, the water appears to run properly through the heat pumps and discharge at a normal flow rate. When I begin to close a water valve (located after the water holding tank) that restricts flow to the heat pumps, the hissing sound is reduced.

The pressure switch gauge normally reads about 20 psi when the water pump is running but at times reaches a level of 80 - 100 psi when the hissing sound starts. I suspect the gauge may be giving a false reading since the discharge end of the water pipe is open and water appears to flow from the discharge end at a high rate.

The water holding tank may not be necessary in my usage, but I had hoped the water holding tank and pressure switch would serve to turn the water pump off if the water pressure reached an abnormally high level. Could the loud hissing sound somehow be related to a problem with my holding tank or pressure switch? 29 May 2015 Jack

Reply:

Watch out: Pressures in a residential water supply system much over 70 psi are dangerous, can burst a tank or pipe, injur someone, or flood the building.

I'd look for a pressure switch or switch sensor problem, and I'd be sure there was a properly installed pressure relief valve on the system.

What's the right water tank air pressure reading when the tank is empty?

Should air bladder read pressure with tank empty.
(June 14, 2015) Ronnie

Reply:

Ronnie

With no water in the pressure tank the internal bladder type water tank is typically set to an air pressure of 2 psi below the pressure control switch cut-in pressure. So if your pressure control is a 30/50 model your tank precharge is 28 psi.

Water tank pressure slowly increases, then rockets to a high number then crashes

My pressure tank is set at 40 psi the pump goes on at 42 psi and goes off at 64 psi. I check this several times running the water. Interesting thing is as the tank charges it's slow from 40 to 50 then rockets up from 50 to 65 then crashes to 50ish and sinks slowly back down to 40. All while the water is running. If I shut the water quickly at 65 it stays at 65. What is going on? (July 4, 2015) Mike V

Reply:

Interesting and strange, I agree. It sounds as if there is a sticky internal bladder in the pressure tank (if that's the type of tank you've got); also the pump output itself may be affected by the pressure level in the system and system pressures in turn by the usage flow rate. Those are some thoughts. Bottom line, I am confused by the data and don't have a sure answer.

Check also for a sticking pressure gauge. Start by hooking up an independent water pressure gauge to monitor pressure.

How do I install a bladder type water tank: need a tank tee? Working pressures?

l am trying to install the above bladder tank its specks are
vessel volume 98.4 liters/26 gallons max working pressure 8.6 bar/125psi

l have no manual and never installed this type of tank

l see there is only one outlet from the tank which seems to me l add a tee from the water inlet but how does this work if the water cannot go in and come out at the same time through the same whole there must be an obvouse reason please help me kind regards alan martin (June 9, 2015) alan@coolmartinresort.php

Reply:

Alan:

Indeed most water pressure tanks using an internal bladder have a single piping connection to which a tank tee is installed to accommodate water from the pump as well as a pressure relief valve and pressure gauge as well as a connection to piping feeding the building.

When the pump is running water is pushed simultaneously into the pressure tank and into the building through the two openings provided by the tee (one into the tank, one into the building). When the pump is not running and water is turned on in the building air pressure in the tank pushes water out of the tee and into the building - until pressure falls low enough to turn on the pump.

For safety you should find the installation instructions from the tank manufacturer and follow them.

Watch out: no residential water tank should actually be operating at the maximum working pressures you cite; typically residential pressures range between 20 psi and 70 psi or perhaps 80 maximum. Higher pressures are unsafe and also cause leaks.

Is it OK to install a bladder type water tank on its side?

Can a bladder tank be installed on its side instead of upright? Will it still work properly that way? (July 21, 2015) Cathy

Reply: no; not unless the tank and its connections, controls, and ports are specifically designed for that position

Probably not. Most manufacturers expect the tank to be upright. You may stress and tear the bladder.

I refer to water supply system pressure tanks.

The smaller internal bladder tanks used as expansion tanks on heating systems (not on water supply systems) can often be installed horizontally or even upside down.