Bladder-type accumulators

Direci-conlacl-iype accumulator or bladder-type accumulator when required... 

Figure 8-9. Manual precharge bladder type accumulator [1].

Gas-filled accumulators, bladder accumulators and resonators which can be used both on the suction and the discharge side of the pump, are most frequently used. They differ in their quality of dampening, prices and the necessity of maintenance. Bladder type accumulators are limited in use due to the chemical and thermical resistance of the bladder materials inside. 

Note that diaphragm-type accumulators can be checked more easily and are more reliable than the less expensive bladder type. Here, a rubberized nylon diaphragm separates the nitrogen charge from the oil. An indicator rod protrudes into a transparent plastic dome and gives accurate, visual indication of tlie true volumes of nitrogen and lube oil. 

The preferred accumulator is the bladder type as shown in Figure 8-9. Body material should be 300 series stainless steel, in accordance with. ASTM A 240. Either a manual precharge valve or automatic charging system can be used, based primarily on the user s preference. The alternative choice is a direct contact accumulator as seen in Figure 8-10. This accumulator has several problems. The gas used to pressure the top of the oil will eventually be absorbed by the oil, which can lead to drain line foam-... 

Pressurized accumulators contain compressed gas on one side of a piston, flexible diaphragm, or bladder. On the other side is the fluid which is discharged as necessary to an external system, normally to provide power. If a piston rod is added to a piston-type accumulator and the system is closed, it becomes a shock absorber using the fluid under pressure to absorb repeated shocks or sudden impulses. 

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