This type of pressure comparison tester can be used to check, adjust, and calibrate both mechanical and digital pressure measuring instrument just by applying identical 

Pressure Comparison Test Pumps are used to generate pressures for checking, adjusting and calibrating mechanical and electronic pressure measuring instruments by comparative measurements. These pressure tests may be carried out in laboratories, workshops or on site at the measuring point. The comparison test pumps LSP 1000-BM and LSP 1600-BM are equipped with two connections for the test specimen and the reference instrument which can be used in any order. If the instrument to be tested and a sufficiently accurate reference measuring instrument are connected to the test pump, the same pressure is applied to the two measuring instruments when the pump is operated. By comparing the two measured values at random pressure values, the accuracy can be verified or the instrument under test can be adjusted. First the pressure is set via an integrated initial (priming) pressure pump. For further pressure generation and for fine adjustment by approaching the measuring points precisely an adjustable volume with precision spindle is available. Another important feature of the LSP 1000-BM and LSP 1600-BM is the rotating spindle that only runs inside the body of the pump. This eliminates the negative effect of a bending torque on a spindle turning outside the body and offers the advantage, especially for use in the field, that the dimensions of these pumps do not change during operation due to the spindle turning. A priming pump is integrated in the basement.