0
A pressure gauge is an instrument that measures the pressure in a vessel, a line, or whatever the pressure gauge is connected to. Pressure gauges come in at least two different types: differential pressure gauges, and absolute pressure gauges.
Differential pressure gauges measure - surprise - DIFFERENCES in pressure. Pressure gauges that read "zero" when not attached to anything would actually be differential gauges that measure the difference between atmospheric pressure and the pressure of whatever they are attached to. Vacuum gauges are differential gauges that measure how far BELOW atmospheric pressure the pressure is in a vessel or pipe. Gauges that measure "gauge pressure" are just differential gauges that are calibrated to measure zero at atmospheric pressure.
Absolute pressure gauges would only read "zero" if they were attached to an absolute vacuum. A common type of absolute pressure gauge is a barometer. Strictly speaking, a Mercury barometer is really a differential gauge that measures the difference between the vapor pressure of the mercury and the surrounding atmosphere, but the vapor pressure of the mercury is so low that the error in treating it as an absolute pressure gauge is generally negligible.
There are many different kinds of gauges used to measure pressure including:
Instruments
hydrostatic - These measure pressure according the height of a liquid in a column. The height of the liquid is proportional to the pressure. Common types of hydrostatic gauges include: manometers, McLeod gauges, and piston gauges.
aneroid - The pressure sensing element may be a Bourdon, a diaphragm, a capsule, or a set of bellows, which will change shape with changes in the pressure of whatever the gauge is attached to. The deflection of the pressure sensing element is read by a linkage connected to a needle or by a secondary transducer. The most common secondary transducers in modern vacuum gauges measure a change in capacitance due to the mechanical deflection. Gauges that rely on a change in capacitance are often referred to as Baratron gauges.
Electronic sensors
thermal conductivity - including two wire and one wire gauges that measure pressure via changes in the thermal conductivity of the wires as they are placed under strain. Something like this is used in a lot of electronic bathroom scales.
ionization gauges - These are primarily used for measurements of low-pressure gasses. They sense pressure indirectly by measuring the electrical ions produced when the gas is bombarded with electrons. Fewer ions will be produced by lower density gases. they have to be calibrated against another type of pressure gauge and depend on the gas being measured.
What else can I help you with?
Gauge pressure and absolute pressure?
Gauge pressure is what you get when you take the reading from your tire pressure gauge. Absolute pressure is the pressure inside your tires plus the atmospheric pressure, which is roughly; 14.7 psi, 101.3 kPa (kilo-Pascals), or one atmosphere. Absolute pressure measures all of the pressure on your tires, inside and out, whereas gauge simply measures the pressure inside the tire.
Is gauge pressure is the sum of true pressure and atmospheric pressure?
No, it is the DIFFERENCE between the true and atmospheric pressures.
Find gauge pressure of faucet on twelfth floor?
Reference pressure less the height.
What is the absolute pressure of -0.2 bar?
Absolute pressure is calculated by adding atmospheric pressure to the gauge pressure. Standard atmospheric pressure is approximately 1.01325 bar, so for a gauge pressure of -0.2 bar, the absolute pressure would be 1.01325 bar - 0.2 bar, which equals approximately 0.81325 bar. Therefore, the absolute pressure is about 0.813 bar.
What is -14.7 psig?
-14.7psig is the gauge pressure of an absolute vacuum.
What is the difference between normal pressure gauge and differential pressure gauge?
A pressure gauge indicates actual pressure and a differential pressure gauge indicates the difference in pressure.
How do you calculate gauge pressure in a system?
To calculate gauge pressure in a system, subtract the atmospheric pressure from the absolute pressure within the system. Gauge pressure Absolute pressure - Atmospheric pressure.
Definition of a compound gauge?
A compound gauge is a pressure gauge that displays both negative and positive gauge pressure measurements. Gauge pressure is a measurement of pressure relative to ambient pressure. For example, if ambient pressure was 14.7 PSI and you were to measure absolute vaccum using a compound gauge, the gauge would indicate -14.7 PSI.
How to convert gauge pressure to absolute pressure?
To convert gauge pressure to absolute pressure, add the atmospheric pressure to the gauge pressure reading. This will give you the total pressure, including the pressure exerted by the atmosphere.
What is the difference between gauge pressure and absolute pressure, and how can one accurately gauge pressure in a system using these two measurements?
Gauge pressure is the pressure measured relative to atmospheric pressure, while absolute pressure includes atmospheric pressure as a reference point. To accurately gauge pressure in a system, one can use a gauge that measures gauge pressure and then add the atmospheric pressure to get the absolute pressure. This allows for a more precise measurement of the pressure within the system.
Does gauge pressure include atmospheric pressure?
Yes, gauge pressure includes atmospheric pressure. Gauge pressure is the pressure measured above atmospheric pressure, so it accounts for the atmospheric pressure as a reference point.
How to find gauge pressure in a closed container?
To find gauge pressure in a closed container, subtract the atmospheric pressure from the total pressure inside the container. Gauge pressure is the pressure above atmospheric pressure.
Can bourdon's tube pressure gauge be used to measure negative pressure?
Bourdon's tube pressure gauge cannot be used to measure negative pressure. This is because absolute pressure must be measured and the Bourdon gauge only indicates the gauge pressure.
Is gauge pressure larger, smaller, or the same as absolute pressure?
Gauge pressure is smaller than absolute pressure.
What gauge measures both vacuum and pressure?
Gauge pressure usually refers to the pressure difference between ambient, atmospheric pressure and the pressure in a vessel or line. A gauge pressure of zero would mean that the vessel or line was at atmospheric pressure. Normally the pressures of interest are ABOVE atmospheric so the gauge pressure is positive. Vacuum gauge pressure measures how far BELOW atmospheric pressure a vessel or line is. As such vacuum gauge pressure may be measured as a negative number - or for convenience it may be reported as a positive number with the caveat that it is "vacuum gauge pressure", meaning that the reported pressure is how far atmospheric pressure is above the pressure in the vessel or line.
Why pressure gauge is called a gauge not a meter?
A pressure gauge is called a gauge because it typically measures pressure relative to atmospheric pressure, which is often considered as the reference point or zero point for pressure measurements. On the other hand, a meter usually measures absolute values without reference to a specific point.
Why diaphragm of a pressure gauge is corrugated?
These are corrugated to increase the sensitivity of the pressure gauge.
