1 hvacr115 – mechanical for gas heat measuring gas pressure

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HVACR115 – Mechanical for Gas Heat

HVACR115 – Mechanical for Gas Heat

Measuring Gas PressureMeasuring Gas Pressure

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Measuring Gas PressureMeasuring Gas Pressure

• To measure gas pressure in the manifold you use the tap in the manifold or the gas valve outlet.

• Tubing can also be slipped over one of the burner orifice hoods.

• Two devices are commonly used to measure gas pressures…

• To measure gas pressure in the manifold you use the tap in the manifold or the gas valve outlet.

• Tubing can also be slipped over one of the burner orifice hoods.

• Two devices are commonly used to measure gas pressures…

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Spring GaugesSpring Gauges

• Bourdon tube gauges are the most common type of spring gauges.

• They have a hollow metal tube that is formed in a curve or arc.

• A pointer is connected to the closed end of the tube by means of levers.

• When pressure is applied through the open end of the tube it tends to straighten out.

• Bourdon tube gauges are the most common type of spring gauges.

• They have a hollow metal tube that is formed in a curve or arc.

• A pointer is connected to the closed end of the tube by means of levers.

• When pressure is applied through the open end of the tube it tends to straighten out.

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Spring GaugesSpring Gauges

• As it straightens out it moves the pointer along a round dial and shows the pressure reading.

• Spring gauges are subject to mechanical damage and must be handled with care. They must also be checked for accuracy on occasion.

• As it straightens out it moves the pointer along a round dial and shows the pressure reading.

• Spring gauges are subject to mechanical damage and must be handled with care. They must also be checked for accuracy on occasion.

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Spring GaugesSpring Gauges

• The pressure gauge is connected to the manifold or the control.

• And the pressure is then indicated directly on the dial.

• Depending on the pressure gauge the reading may be expressed in PSI or in inches of Water Column.

• The pressure gauge is connected to the manifold or the control.

• And the pressure is then indicated directly on the dial.

• Depending on the pressure gauge the reading may be expressed in PSI or in inches of Water Column.

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U-Tube ManometersU-Tube Manometers

• Gas pressure is displayed in inches of water column on the manometer.

• A manometer is simply a U shaped tube made up of a transparent material.

• Both legs of the tube are filled about half way with tap water.

• The water level in the manometer with both ends open the atmosphere is the 0 level.

• Gas pressure is displayed in inches of water column on the manometer.

• A manometer is simply a U shaped tube made up of a transparent material.

• Both legs of the tube are filled about half way with tap water.

• The water level in the manometer with both ends open the atmosphere is the 0 level.

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U-Tube ManometersU-Tube Manometers

• The tubing from the gas manifold or control is connected to one end of the U-Tube and the other end is left open to the room air.

• When gas pressure is applied to the manometer the water in the gas side of the tube is pushed down while the water in the other side rises.

• The tubing from the gas manifold or control is connected to one end of the U-Tube and the other end is left open to the room air.

• When gas pressure is applied to the manometer the water in the gas side of the tube is pushed down while the water in the other side rises.

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U-Tube ManometerU-Tube Manometer

• The manometer then indicates the gas pressure in inches of water column.

• The height of the water column that the gas pressure will support with atmospheric pressure on top of the water column.

• Usually the U-Tube has a ruler in inches between the two tubes for easy measurement.

• The manometer then indicates the gas pressure in inches of water column.

• The height of the water column that the gas pressure will support with atmospheric pressure on top of the water column.

• Usually the U-Tube has a ruler in inches between the two tubes for easy measurement.

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U-Tube ManometersU-Tube Manometers

• The scale readings extend both above and below a zero point.

• The pressure reading is obtained by adding the height of the water column above the zero point, the the distance BELOW the zero point.

• The scale readings extend both above and below a zero point.

• The pressure reading is obtained by adding the height of the water column above the zero point, the the distance BELOW the zero point.

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U-Tube ManometersU-Tube Manometers

• You must initially line up the water level in the two legs of the manometer with zero on the scale with both ends open to the atmosphere.

• You must initially line up the water level in the two legs of the manometer with zero on the scale with both ends open to the atmosphere.

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Gauge and electronic manometersGauge and electronic manometers

• There are newer manometers that are electronic or gauges. These are replacing the U-Tubes on most service trucks.

• Studies have shown that if taken care of properly these will serve the same purpose. However, the U-Tube is still the most accurate.

• There are newer manometers that are electronic or gauges. These are replacing the U-Tubes on most service trucks.

• Studies have shown that if taken care of properly these will serve the same purpose. However, the U-Tube is still the most accurate.

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U-Tube ManometerU-Tube Manometer

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Gauge SetGauge Set