Diaphragm Accumulator. The diaphragm-type accumulator consists of a diaphragm secured in the shell, which serves as an elastic barrier between the oil and gas(see Figure 11-7). A shutoff button, which is secured at the base of the diaphragm. cov ers the inlet of the line connection when the diaphragm is fully stretehed. I his pre vents the diaphragm from being prcssed into the opening during the preeharge period. On the gas side, the screw plug allows control of the charge pressure and charging of the accumulator by means of a charging dcvice.