We have two kinds of pressure gauges with red drag needle for different customer needs. Both types of pressure gauges has a normal black hand indicating the pressure value at current time, and a red pointer serving as a warning.
First type, the red pointer needs to be adjusted to the warning pressure value position in advance, and it will stay at same position. When the pressure comes in, you can compare the black pointer and red pointer positions to tell if the system has overtaken the maximum pressure value. Some also prefer to print red line mark on dial or lens in corresponding position to the maximum pressure value warning point, to replace the red pointer. The function is same as mentioned previously.
The second type, red pointer can be pushed by the normal black pointer and serves as a memory. With the increase of the measured medium pressure, black pointer also drives the rise of red pointer. When the pressure decreases, the red pointer remains in place. When there is no pressure intake, the black pressure indicator will reset to zero, while the red memory pointer will stay at the position, the maximum pressure value position black pointer has been gone, so that the staff can clearly know the value of the working pressure display. This makes it possible to record what is the maximum pressure value of the pressure system during unmonitored periods. When it is necessary to re-record the maximum pressure, staff can adjust the red pointer back to the position of the black pointer.
