Refrigeration system is a cooling system which ejects the heat and transfers it from low energy reservoir to the high-temperature region. It has vast application as a household refrigerator, industrial refrigerator and air conditioning. Refrigerator gauge is used in the refrigeration system. Heat pumps are also implanted in them to pump out the heat output and maintain the cooling system of refrigerants.

The most common type of refrigeration system is manifold gauges or air conditioning gauges.

Instrumentation of Manifold Gauges:

Manifold gauge detects the pressure difference of the air conditioning system as it operates. A manifold gauge usually consists of the manifold block on which two hand valves are fixed, there are refrigerant hoses and two pressure gauges.

• HAND VALVES: Two hand valves which are fixed on the manifold gauge maintain the flow of refrigerant.
• PRESSURE GAUGES: The pressure gauges are connected by the hand valves. The pressure gauges are of low-pressure side and the high-pressure side
• HOSES: There are three hoses attached at the bottom of the pressure gauge. Refrigeration system may be of a single hose or a dual hose. It consists of a compressor and stimulates a cooling system. It expels the warm air from the room and pulls air within the room.

Digital Pressure Gauge:

It is a more reliable form of the better gas pressure gauges. It converts the applied pressure into a signal and we can read them numerically. IT works on the principle of piezoelectric sensors.

The common type of Digital Pressure Gauge is Flush Digital Pressure Gauge.

Instrumentation of Flush Digital Gauge:

It is used to detect the pressure in viscous media to prevent blocking and remove the residual waste. It consists of the following parts:

• LED/ LCD: In digital pressure gauge the dial is replaced with a led screen which shows the number.
• HIGH-PRESSURE SENSOR: It detects the high pressure in the form of electric signal.
• LOW PRESSURE SENSOR: It detects the low pressure in the form of an electric signal.
• STORAGE MAXIMUM/MINIMUM PRESSURE: With the digits review, the graph will show continuously peak which detects the low or high fluctuation in pressure

3. Vacuum Pressure Gauge:

It is an electronic device widely used in laboratory and industries. It creates the vacuum pressure of 10-3 MILLIBAR. Its reading is shown in a negative value. For Example: If we give a pressure of 0.1 Pa then vacuum pressure gauge give reading as -0.1.

Instrumentation of Low Vacuum Pressure Gauge:

• MICRO ELECTRO MECHANICAL SYSTEM: It is a micromachining instrument and has a silicone surface.
• VIBRATING ELEMENTS: these are the silicone resonating particles.
• VARIABLE CAPACITANCE: Vacuum Pressure Gauge has diaphragm lining. When pressure exerts on the diaphragm lining it changes the capacitance value depending upon the medium and we can detect the change in pressure.
• VARIABLE STRAINS: These strains are very sensitive to resistance and thus detect the pressure change.

Temperature Calibrators:

It is widely used industrially and commercially. It calibrates the temperature of a system by using dry block, liquid bah and others multifunction calibrators.

We can calibrate the temperature of probes by comparing it with standard known temperature, There are the chances of errors because every system is affected by its surrounding, These types of calibration take place in the vacuum chamber.