Fridge freezer refrigeration manifold gauges re-gassing topping up recharge

I use the single gauge manifold as below its been excellent for my uses I use it for system testing refill through it and vacuum down.

The gauge is used to measure the pressure in the system ( low side ) suction, in PSI or bar if you have the correct gauge for the gas being used the temperature scale can be used to find the evaporator temperatures at certain pressure to aid in diagnostics. But this gauge it mainly used by me for checking gas pressures and good operation of the compressor.

When putting the system under a vacuum i use the gauge on my vacuum pump this reads in milibar and is much more sensitive to pressure changes and even very minor leaks can be found. Well worth checking as ive gone to customers houses after other techs and found minor leaks that shut the fridge freezer down again weeks or a couple of months after.

The gauges when connected give a reading instantly the on off tap only opens the valve to the centre valve for topping up or vacuuming down purposes. 

See photo below to help visualise this , the gauges will always read pressure measurement.