|
Simplest means of providing a restriction
in the socket. This device is threaded into a tapped
hole.
Its size is selected base on the viscosity of the
pressure fluid, rapidity of pressure fluctuations and
the amount of dampening effect desired.
Throttling Devices
A throttling device should be used when a pressure gauge
is subjected to rapid pressure fluctuations, which make
the gauge difficult to read because of rapid pointer
movement. Such a device reduces pressure impact, slows
the speed and range of pointer movement, and prolongs
gauge life.
Throttling effect is obtained by installing a
restricting orifice between the gauge socket connection
and the bourdon tube. Several types are available:
throttle screws, pressure snubbers, pulsation dampeners,
Pressure Snubber
Used for
dampening and filtering, the snubber has a metal disc
available in four standard grades of porosity. The one
best suited for the application can be selected from the
chart, using the same guidelines as for throttle screws.
Due to the large filter area, the snubber has less
tendency to clog than orifice-type devices. All-metal
construction permits the snubber to be washed in a
variety of common solvents.
The simplest
means of providing a restriction in the socket, a throttle screw, should
be ordered with the gauge. Threaded or pressed into an instrument
socket, the throttle screw orifice selected is based on the viscosity of
the pressure fluid, rapidity of the fluctuations, and the amount of
dampening effect desired. A smaller orifice should be used for low
viscosities, high frequencies, high pressure and reduced pointer
amplitude. To accommodate these variables, throttle screws are available
in these sizes: 0.006, 0.0135, 0.020, 0.031, 0.040 and 0.070 inches, in
brass or stainless steel. When orifice size or service is not specified,
a 0.031 -inch orifice will be supplied.
Links
|
