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911-481  Rev.  F    10/04 

Page: 1 of 2  

 

3400 SERIES ACCUMULATOR TANK 

GENNERAL INSTALLATION INSTRUCTIONS  

This manual does not address water boost applications.  For help, please contact SHURflo. 

Read this manual carefully.  Failure to follow instructions could cause serious bodily injury and/or property 
damage.  

Do not exceed 100 psi [6.8 bar] on the 3400 series.  

WARNING:

 Hazardous pressure. To prevent possible serious or fatal injury and/or damage to equipment, 

system pressure 

MUST BE LESS THAN 100

 pounds per square inch (psi) [6.8 bar] under any 

circumstances.  Failure to follow instruction can result in tank blowup.  If system discharge pressure can 
exceed 100 psi [6.8 bar], install a relief valve capable of passing the full pump volume at 100 psi [6.8 
bar].  Install relief valve in pump supply line to tank, as close to tank as possible. Consult installer or 
licensed plumber for correct relief valve.  Install system according to local codes. 

The SHURflo Accumulator tank is a bag-type pressure storage vessel and/or a pulsation dampening device.  

The accumulator is precharged to 20 psi [1.4 bar] for shipping.  Do not exceed this pressure for long-term 
storage, shipping or system non-use.  

An accumulator placed in the pressurized side of a potable water or reverse osmosis system (with a 
demand pump), can minimize pump cycling.  The accumulator contributes to longer pump life, less noise, 
less amperage draw, and reduced water pulsation.  The most efficient use of the accumulator occurs with 
the precharge pressure set at the SAME pressure as the pumps' pressure switch "turn 

ON

" setting.  

Typically, a 40 psi [2.7 bar] pump will "turn 

ON

" at 20 psi [1.4 bar]. Therefore, the precharge should also be 

20 psi [1.4 bar].  The precharge must be set in a "static" condition (pump off and at least one water fixture 
opened to atmosphere). 

NOTE: 

If the accumulator precharge exceeds the pump "turn 

ON

" pressure  by "a couple of psi," the 

volume of pressurized liquid within the accumulator will be reduced. 

• 

The precharge valve stem cap 

MUST 

be tight to prevent a leak down of pressure.  It is recommended the 

precharge be checked on a monthly basis.  

• 

The accumulator may be mounted anywhere in the pressurized cold water side of the plumbing.  The port 
is non-directional in flow, allowing mounting in any position.  

• 

CAUTION:

  Do not freeze or mount near a high heat source.  Extreme temperatures may lead to tank 

explosion and serious injury. 

GENERAL INFORMATION

 

• 

Keep safety labels in good condition.  Replace missing or damaged safety labels. 

• 

When servicing tank, BE SURE the pump (power source) is disconnected.  Release all water pressure before 
working on tank or system.  Release all precharge pressure by depressing the valve core.  

• 

In areas where temperature is high for long periods of time, tank precharge may increase. This may 
reduce tank drawdown (amount of stored water at pressure). If this occurs, reduce precharge pressure 2 
psi [14kPa] below pump "turn 

ON

" pressure.  Cold temperatures may require more air pressure. 

TO CHECK TANK AIR CHARGE

 

If drawdown decreases significantly, check as follows: 

1. 

Shut off electric power to pump, open faucet near tank, and drain completely. 

2. 

At air valve, check precharge with tire gauge. Precharge should be at pump "turn 

ON

" pressure setting. 

3. 

If precharge is more than 2 psi [14kPa] below the "turn 

ON

" pressure, add air to tank. Use air compressor or 

portable air storage tank.  If precharge is above "turn 

ON

" pressure, bleed off the appropriate amount. 

4. 

Use soap or liquid detergent to check for air leaks around air valve. Continuous bubbling indicates leak. 
If necessary, install new core in air valve (same as used for automobile tires). 

5. 

If tank is filled with water (waterlogged), the bladder is leaking.  Replace bladder. 

 

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