Pressure

Question 1

Pressure

Answer 1

Force per unit area; usually measured in pounds per square inch(psi), or by the height of the column of water or mercury which the force will support (in feet, inches, or millimeters).

Force applied uniformly over a surface measured in force per unit area.

Question 2

PSI/PSIG

Answer 2

Pounds per square inch / Pounds per square inch gauge.

1 pound per square inch (psi) pressure upon a surface that has 100 square inches (sq. In.) has accumulated force 100 pounds. 1psi X100Sq in. = 100 lbs.

Question 3

PSIA

Answer 3

Pounds per square inch absolute

Question 4

Atmospheric Pressure

Answer 4

The pressure exerted on the earth’s surface by the weight of the air and moisture above it. A unit of pressure equal to about 14.696 psi, or 29.92 inches Hg mercury, at 32F degrees at sea level. Also call barometric pressure. Pressure is measured in pounds per square inch.

0 psig (pounds per sq in. Gauge)

Question 5

Absolute Pressure PSIA

Answer 5

The common gauge expresses a pressure in pounds Berlings square inch called gauge pressure. When the gauge is open to the atmosphere it reads zero. Absolute pressure is 14.7 at sea level. It varies with location and atmospheric conditions. It is accurately indicated by barometer. Absolute pressure can be zero only in a perfect vacuum.

Question 6

Gauge pressure

Answer 6

Pressure expressed in pounds per square inch gauge (psig). Readings in psig measure only pressures above atmospheric. Gauges are calibrated to read zero psig at atmospheric pressure.

Question 7

Inches WC (water column)

Answer 7

Water column, abbreviated as WC. A unit used for expressing pressure. One inch water column equals a pressure of 0.578 oz/in2. 1psi=28inches of water column (WC)
1”WC = 1/28 psi
.1”WC= 1/280 psi
.01” WC= 1/280 psi

Question 8

Inches Hg

Answer 8

Inches of mercury

2inches Hg. (Mercury)=1psi

Question 9

Inches of Hg VAC

Answer 9

Inches of mercury in a vacuum. An example On a compound gauge 30”Hg VAC = 0 PSIA.

Question 10

Inches of mercury

Answer 10

A unit used in measuring pressures. One inch of mercury column equals a pressure of 0.491 lb/in

Question 11

Micron (u)

Answer 11

A metric unit. For length it is one millionth (1/1000,000,000) of a meter (39 inches). There are 25,400, microns in one inch. For pressure it is one 25,400th (1/25,400) of and inch of mercury.

Question 12

Force

Answer 12

That which produces, or tends to produce, motion. It is accumulated pressure and is expressed in pounds. If the pressure is 10 psi on a plate 10 sq in. area. The force is 100lbs.

Is the capacity to work or cause physical change.

Question 13

Compound gauge

Answer 13

An instrument used for measuring pressures both above and below atmospheric pressure.

Question 14

Delta P

Answer 14

Difference in pressure from one side of a surface to the other side of the same surface.

Question 15

Weight of Water

Answer 15

62.4 pounds per cubic foot (lb/ft3). A cubic foot (7.48 gal) exerts a downward pressure of 62.4 lb/ft2 when in actual cube shape.

Question 16

Standard condition

Answer 16

Air at sea level at 70F when the atmosphere’s pressure is 14.696 PSIA (29.92in Hg) air at this condition has a volume of
13.33ft3/lb.

Question 17

Conversion of psi to Mercury (Hg)

Answer 17

1 psi = 2.036 in. Hg

Question 18

Dry Air

What is atmosphere made of?

Answer 18

78% Nitrogen
21.% oxygen
1% other gases

Question 19

When evacuating a system what is a good pressure?

Answer 19

500 to 1000 microns

Question 20

Pressure always goes from height to low

Answer 20

The way pressure goes.

Question 21

Is pressure energy?

Answer 21

Yes

Question 22

Pressure at the top of the stratosphere 19 miles

Answer 22

Pressure = .32” in. Hg

Question 23

Atmospheric pressure decreases about 1 inch per ________

Answer 23

1000 feet of altitude

Question 24

Measurements of pressure

Answer 24

2” hg = 1psi

29.92” hg(at press) = 15psia(14.7psia

Question 25

Bourdon tube

Answer 25

Used in most analog gauges

Question 26

Natural gas is burned at ____ Water column

Propane is burned at 11in WC

Answer 26

3.5

Question 27

Calculate a compression ratio

Answer 27

One of the only times you will use absolute pressure. Always add 15 PSIA

Hight side. 250psig + 15psia
———————-
Low side. 80 psig + 15psia

256
——= 2:8
95

Question 28

Kilo pascal

Answer 28

Unit of pressure 6.89 per 1 psi