Additel ADT 959A [ADT959A-AF] Hydraulic Ultra-High Pressure Test Pump, Autoclave F-250-C Female, 40,000 psi (2,800 bar) - Diethylhexyl Sebacate. The new Additel 959AAF Hydraulic Pressure Test Pump is a benchtop pressure pump designed to generate pressure to 40,000 psi (2,800 bar). This pump incorporates a dual-piston system which is ideal for filling large volume workload with the hand pump and providing smooth increase and decrease of pressure with the high pressure, fine adjust screw press. The 959A test pump incorporates an isolation valve which isolates the calibration volume from the check valve associated with the hand pump. Because the check valve can often be a source of leaks and maintenance, the isolation valve provides more stable measurements and reduces potential maintenance of the pump. The Additel 959A-AF is an ideal comparison test pump for calibrating pressure measuring instruments such as test gauges, indicators or transducers.