Drawing Number: 21110
Revision: B
OPERATION MANUAL FOR
QUARTZ PRESSURE SENSOR
Series 118 & 119
2
3.2
PREPARING NEW MOUNTING
PORTS
Refer to the installation drawing provided in this
manual for instructions on mounting hole preparation.
For best results, do not deviate from the steps
outlined in this drawing.
To assist new mounting port preparation, PCB offers
the 040B20 Tooling Kit (040B21 for metric mount).
These installation kits provide all of the necessary
tooling required to drill, ream, and tap the mounting
ports for proper installation of the 108, 109, 118 and
119 Series transducers.
Use good machining practice in preparation of the
mounting port, paying particular attention to the seal
surface. It is important that this surface be perfectly
smooth and free from tool chatter marks, nicks and
other imperfections which might cause leaks at high
pressures.
3.3
RECESSED MOUNT
The recessed installation is shown in the Recessed
Mount figure. This type of mounting protects the
sensor diaphragm from the effects of high-flash
temperatures and particle impingement due to blast
effects, thereby prolonging sensor life.
The recommended range of passage diameters is
0.090 to 0.125 inch (2.29 to 3.18 mm) diameter.
The limitation in this type of installation lies in the
frequency-limiting effects of the passage due to its
length.
The passage behaves like an underdamped second
order
system;
the resonant frequency being
determined by the passage length. The length may
have a limiting effect on pressure pulse rise time and
cause passage ringing in cases where the passage is
too long.
Recessed Mount
The following relationship approximates this resonant
frequency (f
r
):
(Hz)
L
4
V
f
r
(EQ. 1)
Where: f
r
= Resonant frequency of passage (Hz)
V = Velocity of sound in air (ft/sec)
L = Length of column (ft)
For air at room temperature, (EQ. 1) becomes:
L
00
3
3
f
r
(EQ. 2)
Where: L = Passage length (in)
0.010
MIN
