67.RECOGNIZING PRESSURE DROP IN COMPRESSED AIR LINES

Compressed is a friendly and reliable energy source used for many applications but sometimes not enough thought is given to the “pressure drop” when using the air.   Pressure drop is the loss of pressure due to energy loss in transmitting the compressed air.  Often pneumatic machines will run slower or not at all and blow off products not work as well simply because the pressure drop is not accounted for.

For any application, you need to know the air consumption of the end product and to assure the supply line is large enough to be certain that he pressure drop is not too high, especially if the loss of pressure falls below the minimum required for the device using the compressed air.   There are two types of pressure drops: natural and unintended.

Natural loss occurs as the compressed air travels through  the airline once you know the air consumed at the end use or uses.  On line software exists to easily calculate these natural losses based on the size of the piping, bends, and fittings encountered as the compressed air travels through the pipe.   Pipe size should be large enough to minimize pressure loss.  Hence planning for the proper size of piping should be done in advance by recognizing and accounting for all uses.  If something does not work when attached to a compressed air line, the first thing you need to check is the air consumption of the product against the line size.

Unintended loss occurs when you add to the air line, a set of fittings that are not designed for the intended flow and even a small diameter hose to a large airline.  That small hose and undersize fittings would be like trying to push and elephant through a straw.  The pressure drop can be quite high.  It has become quite fashionable to use easily connect plastic hose and fittings and use whatever might be readily available in manufacturing operation.  It is not unusual to see 8 mm hose connected from a 1″ air line to a product using a lot of compressed air, without realizing the large pressure loss in the hose.   The simple solution would be larger hose and accompanying fittings.

So in a pneumatically operated device is not operating as it should, the first thing that should be checked is “pressure drop”.