Test 1 Flashcards
Pass the Test
1 atm in psi
14.7 PSI
What is 1 psi in “H2O
27.7”H20
Three accessories for pressure gauges
Oil filled, snubber, and chemical seal
Use for snubbers on pressure gauges
Reduce oscillation in measurements (restricts flow in and out of gauge)
Use for oil fill accessory in pressure gauge
Reduce effects of plant vibrations (reduces shock and extends gauge life)
Use for chemical seal
Protect internal components from flow (corrosive, hot, slurry)
1 psi to “Hg
2.04 “Hg
1 psi to kPa
6.895 kPa
1 bar to psi
14.5 psi
1 bar to kPa
100 kPa
1 “H2O to mmHg
1.87 mmHg
1 “H2O to cmH2O
2.54cmH2O
1 kg/cm^2
14.22 psi
1 atm to bar
1.0135 bar
1”Hg to “H2O
13.61 H2O
Does volume matter for pressure?
No
What is elevated based range?
When the LRV is below zero
What is zero based range?
When the LRV is zero
What is LRV?
Lower Range Value
What is URV?
Upper Range Value
What is suppressed based range
When the LRV is above zero
What is the first step in a lab procedure?
Obtain the instruction manual(s)
What mainly determines the cost of a pressure gauge?
Accuracy
What are bourdon tubes usually made of?
Stainless steel (varying grades) or brass
What are the three types of bourdon tubes?
C spring, spiral, helical
What is the purpose of pressure elements?
Create mechanical motion from input pressure
Accuracy of C spring
+/- 1% of span
Typical range of C spring
0-10 psi, up to 0-20k psi
What does the c shape in a c spring want to do as pressure is applied to it?
Straighten out
Accuracy of spiral bourdon tube
+/- 0.5% of span
What is span
URV-LRV
Typical range of spiral bourdon tube
0-10 psi, up to 0-100k psi
Accuracy of helical bourdon tube
+/- 1% of span
Typical range of helical bourdon tube
0-30, up to 0-80k
Min and max ranges of bellows element
Min: 0-2.5”H2O, Max: 0-2000 psi
What easily damages bellows elements
Too much pressure
Accuracy of bellows element
+/- 2% of span
Min and Max range of diaphragm type element
Min: 0-0.5”H20, Max 0-3000 psi
Accuracy of diaphragm type element
+/- 1% of span
When is a pneumatic pressure transmitter used
When a signal is needed in a control loop
What does a pneumatic pressure transmitter reproduce process pressure as?
Proper signal pressure
What is a flapper nozzle used for
Convert mechanical motion to standard pneumatic signal
What is the heart of near all pneumatic transmitters/controllers
Flapper nozzle/error detector
What is the standard pressure applied to a fixed orifice/restriction
20 psi
Three Types of Manometers
U Tube, Well, Incline
Characteristics of U tube manometer
Clear tube bent into a u shape, labeled with graduated scale placed between vertical columns/legs, with scale marking going up above and below zero point
Characteristics of Incline type Manometer
Reservoir serving at one end, measuring column at an angle from the horizontal to reduce vertical height
Characteristics of Well type Manometer
Vertical glass tube connected to metal well, measuring liquid in well at same level as zero point on the tube scale
What is a barometer
Type of manometer used to measure atmospheric pressure
What is a diaphragm
a
mechanical pressure
sensor consisting of a thin,
flexible disc that flexes in
response to a change in
pressure
What is a capsule
a mechanical pressure sensor consisting of
two convoluted metal diaphragms with their outer edges
welded, brazed, or soldered together to provide an empty
chamber between them
