precharged. The main disadvantages of the piston types of accumulator are that they are expensive to manufacture and have practical size limitations Piston and seal ftic- tion may also be a problem in low-pressure systems. Also, appreciable leakage tends to occur over a long period, requiring frequent precharging, Piston accumulators should not be used as pressure pulsation dampeners or shock absorbers because of the inertia of the piston and the friction of the seals. The principal advantage of the on accumulator is its ability to handle very high or low temperature system lu- ids through the use of compatible O-ring seals.