Instructions of Pressure Gauge

INSTRUCTIONS OF PRESSURE GAUGE

 
Mounting
Different types of cases are possible according to position of the connection.

TYPE B
 

TYPE W
 

TYPE D
 

TYPE P
 

TYPE U
 

Direct mounting Bottom connection  without flange

Wall mounting Bottom connection with back flange

Direct mounting
Back connection  without flange

Flush panel mounting
Back connection  with front flange

Flush panel mounting
Back connection  with U-clamp

 
Position

Always vertical, otherwise specify the direction and angle.
A pressure gauge is calibrated in a vertical position. The pointer may be out of zero if the instrument is horizontal, chiefly for low pressure ranges. However, this is not a defect.

 position.jpg
Threads
Standard threads are: Taper PT (BSPT) or Taper NPT or Parallel PF (BSP)
 
Parallel PF (BSP)
Place a gasket between the end of the thread and around the spigot.
thread.jpg
Taper PT (BSPT) or Taper NPT
Tightness is achieved metal on metal without any gasket. However, a seal tape wound around the thread prevents leakage and provides a better tightness and makes the screwing easier.
Oxygen
For oxygen service, the parts of gauge must be oil-free. Specify by ordering.  
   
Installation
Never install the pressure gauge by turning the case but mount it with a wrench by means of the hexagon or flats provided on the socket. installation.jpg
Isolating Cocks
A pressure gauge must never be mounted without an isolating cock. isolation.jpg
Vibrations

Vibrations of the pressure gauge must be avoided to prevent excessive wear of the mechanism.  It would be better to set the gauge on a rigid support on which the vibrations of the pipe have no influence. If this mounting is impossible, choose the pressure gauge with liquid filled.

A flexible small diameter capillary can also be placed between the gauge and diaphragm seal.  A capillary can also be used as a vibrations or pulsations damper.
vibrations.jpg
   
Pressure Pulsations

In the case of pressure measurements of pulsating fluids, a damper should be fitted between the pressure gauge and the pipe.

Adjustment of damper will be done on line where the gauge is used, according to the pressure pulsations.
pulsations.jpg
Corrosion

If stainless steel do not provide sufficient guarantee against corrosion, place a diaphragm seal between gauge and pipe.

Parts of the diaphragm seal in contact with fluid (lower flange and diaphragm) are made of a material withstanding corrosive fluids: stainless steel, PP, PVC, PTFE, PVDF…etc. or coated with corrosion-proof materials (Teflon, halar, Kel F…etc.).
corrosion.jpg
 
Temperature

Excessive temperatures must be avoided.
Standard pressure gauge with brass connection must not be subjected to permanent temperature over 60℃. Special weld on the joining of tube and socket can make the gauge use for process temperature within 120℃ (Specify when ordering).
All stainless steel pressure gauge can be durable for process temperature within 120℃. The pressure gauge, whose case and socket are sealed by weld, can be used for process temperature within 180℃ (Specify when ordering).

Siphon, capillary or heat reduction fitting should be placed between the gauge and the pipe or tank in which filled with hot media.
temperature.jpg
 
Full Scale Range

The full scale range of pressure gauge should be 1.5 to 2 times of maximum process pressure. 
Using overpressure the full scale range is not allowed.

full_range.jpg