Fundamentals of Industrial Control WEEK 3. This week : Pressure Measurement Terminology Pressure Sensor Technology . How was it last Week?. Recap of last Week: Remember the terms? Types of Level sensors Did we miss any? Homework done?!. What are Sensors?. Sensors:
This week : Pressure Measurement
Pressure Sensor Technology
Recap of last Week:
Remember the terms?
Types of Level sensors
Did we miss any?
Primary Role: Collecting and Sending Data
about a measured variable
Comparing data to what is to what it should be
Allows us to make decisions
Used for Vacuum reference principally
30.65 inches of mercury = 1 Atmosphere
Pounds per square inch Gauge
= reference to atmosphere on earth
Pounds per square inch Absolute
= Reference to “Space Vacuum”
PSIG= PSIA+ 14.7
Diaphragm elements are circular-shaped, convoluted membranes. They are either clamped around the rim between two flanges or welded and subject to the pressure of the media acting on one side. The deflection caused in this way is used as a measurement for the pressure and is indicated by a pointer. Compared with bourdon tubes, these diaphragm elements have a relatively high activating force and because of the circular clamping of the element they are insensitive to vibration. The diaphragm element can be subjected to higher overload through load take-up points (by bringing the diaphragm element against the upper flange). Moreover, the pressure gauge can also be protected against extremely corrosive media by coating with special material or covering with foil.Wide connection ports, open connection flanges and purging plugs can be integrated for measuring highly viscous, impure or crystallizing media. Pressure ranges are between 0...16 mbar and 0...40 bar in accuracy class 0.6 to 2.5.
Bourdon tubes are circular-shaped tubes with an oval cross-section. The pressure of the media acts on the inside of this tube which results in the oval cross section becoming almost round. Because of the curvature of the tube ring, the bourdon tube bends when tension occurs. The end of the tube, which is not fixed, moves, thus being a measurement for the pressure. This movement is indicated by a pointer. Bourdon tubes bent at an angle of approx. 250° are used for pressures up to approx. 60 bar.
For higher pressure, bourdon tubes are used which have a number of superimposed coils of the same diameter (i.e. helical coils) or helical-shaped coils (i.e. helical springs) at one level. Bourdon tubes can only be protected against overload to a limited extent. For particularly difficult measuring operations, the Wika pressure gauge can be provided with a chemical seal as a separation or protection system.
The pressure ranges are between 0...0.6 and 0...4000 bar with a reading accuracy (or accuracy class) from 0.1 to 4.0%.
Inner ScaleOuter Scale
Inner ScaleOuter ScaleFigure IntervalsMinor Grad.Figure IntervalsMinor Grad.
0/9 oz./in.2 0/15 in. H2O 1 0.2 5 0.2
0/20 oz./in.2 0/35 in. H2O 5 0.5 5 0.5
0/35 oz./in.2 0/60 in. H2O 5 0.5 10 1
0/60 oz./in.2 0/100 in. H2O 10 1 10 1
Size63mm (2.5"), 100mm (4")
Case304 stainless steel, dry (1008A), or liquid filled (1008AL)
Ring304 stainless steel, crimped
DialBlack figures on white background, aluminum
Bourdon tube"C" shaped bronze (vac.-600 psi and compound) Helical bronze (1000 psi-6000 psi) Helical stainless steel (10,000 psi-15,000 psi)
MovementPatented PowerFlexTM with polyester segment
SocketBrass, with O-ring case seal
RestrictorBrass throttle plug 0.013" orifice in all ranges (except vacuum and 15# psi ranges)
Connection.25 NPT lower and back
RangesVac. thru 15,000 psi and compound. Equivalent metric ranges available
AccuracyASME B40.1, Grade B, 3-2-3
Operating temperatureDry gauge: -40° F to 150° F Glycerine filled: 20° F to 150° F Silicon filled: -40° F to 150° F
CaseSealed case, field-fillable (LJ) Silicone filled (GV)
Mounting hardwareU-clamp (UC), front flange (FF), retrofit flange (RF)
SocketThrottle plugs 0.007", 0.02", 0.063"
are .5% accuracy
Pressure psiCompound psi
0/15 30" Hg/15 psi
0/30 30" Hg/30 psi
0/60 30" Hg/60 psi
0/100 30" Hg/100 psi
0/160 30" Hg/150 psi
0/200 30" Hg/300 psi
0/600 30/0 in. Hg
0/800 34/0 ft H20
0/5000 NOTE: Equivalent standard kg/cm2, and kPa metric ranges are available.
Pages 95-147 Temperature and Weight
In trouble…Email me!!