Functional description

P&ID BM55-2U

The intended use of the Pressure control panel BM55-2U is the expansion of a gas from a gas source and the distribution of the gas with adjustable outlet pressure.

The 2U pressure control panels are two-sided pressure control panels with a switching mechanism (2U). The switching mechanism switches automatically from the side that is currently in operation to the reserve side when the gas supply situation requires it. The lever position of the switching mechanism indicates which side is the operational side and which the reserve side.

You select which side of the pressure control panel is to be used by operating the switching mechanism:

The switching mechanism links the pressure regulators with each other by their pressure adjusting spindles. If you shift the lever from the upper position to the lower position, for example, this reduces the outlet pressure in the pressure regulator on the left and increases the outlet pressure in the pressure regulator on the right. The right-hand side is thus currently the operational side. The automatic and interruption-free switchover to the reserve side on the left, where the pressure is set lower, takes place as soon as the outlet pressure on the operational side (on the right) drops to below that of the reserve side. This can happen as a result of the constant emptying of the gas cylinders on the right and thus the falling of the inlet pressure on the operational side to under the level of the reserve side or as a result of very large amounts of gas being drawn, thus lowering the outlet pressure on the operational side quickly. Thus, if the reserve side goes into operation, the outlet pressure made available by the switching panel is lower than the outlet pressure made available by the operational side beforehand. The manual operation of the switching lever helps here: it increases the outlet pressure of what has been the reserve side, thus converting it into the operational side, and at the same time reduces the outlet pressure of what has been the operational side up to now. As a result, it becomes the reserve side. In the case of two-stage switching panels, the fall in the outlet pressure as a result of the switchover is barely noticeable. The outlet pressure is kept largely constant by means of the second regulating stage. All single-stage automatic switching panels have an inlet pressure gauge for each pressure regulator to indicate the current inlet pressure. Since the pressure regulators are linked to each other on the outlet side, only one pressure regulator has the outlet connection. The other one has the outlet pressure gauge.