Advantages of Pneumatic instrument:
Intrinsically safe:
Pneumatic instruments can not generate electric sparks. So, these instruments are used in classified industrial environments where there are gases, liquids, powders and explosive dust.
The air can be charged more safely than it is non-flammable and does not short-circuit or explode, so protection against these two things is quite easy, unlike the electrical system that could cause fires.
Self purging:
Its continuous bleeding of compressed air from the ventilation holes in the pneumatic relays and nozzles acts as a natural clean purge for the interior of the instrument, preventing the entry of dust and vapor from the outside with a slight positive pressure inside the box of the instrument.
Pneumatic instruments mounted inside larger enclosures with other devices tend to protect them all by providing a positive pressure air purge for the entire enclosure.
Free energy source:
Pneumatic instruments can operate with compressed gases other than air. This is an advantage in remote natural gas installations, where natural gas itself is sometimes used as a source of pneumatic “power” for instruments.
As long as there is compressed natural gas in the pipeline to measure and control, the instruments will work. No air compressor or power source is needed in these installations.
Easy channelled:
Air is a substance that passes easily or moves from one place to another through a small, long and small pipe.
Environment-friendly:
Pneumatic instruments can operate in high temperature and high radiation environments that could damage electronic instruments.
Although it is often possible to “harden” electronic field instruments to such harsh conditions, pneumatic instruments are virtually immune in nature.
Easy utilized:
The easy air is used directly to clean surfaces such as metal and machinery, or indirectly, that is, through pneumatic equipment to produce certain movements.
Disadvantages of Pneumatic instrument
Calibration accuracy:
Sensitivity to vibration, temperature changes, mounting position and the like affect calibration accuracy to a much greater extent for pneumatic instruments than for electronic instruments.
Cost:
Compressed air is an expensive utility - much more expensive per watt-hour equivalent to electricity, which makes the operating cost of pneumatic instruments much higher than that of electronics.
The installed cost of pneumatic instruments can also be quite high, given the need for special pipes (stainless steel, copper or resistant plastic) to bring air supply and pneumatic signals to distant locations.
Leakage problem:
The air pressure is maintained in the hard work. That’s why we need a seal so that the air does not escape. Leaking the seal can cause loss of energy. The pneumatic equipment must be equipped with airtight equipment to minimize the leakage of compressed air in the system.
Potential noise:
Pneumatic with open system, which means that the air that has been used will be expelled from the system, the air will come out quite loud and noisy, which will cause noise, especially in the exhaust tract. The solution is to put a silencer in each discharge line.
Air Damping:
The volume of air tubes used to transmit pneumatic signals over distances acts as a low pass filter, naturally dampening the response of the instrument and thus reducing its ability to respond quickly to changing process conditions.