Have a Plan and Stick to It: Common Compressed Air Drawing Symbols

Mike Tyson once said “everyone has a plan ‘til they get punched in the mouth”. I do believe it’s always important to have a plan, but hopefully your line of work does not involve anyone punching you in the mouth. If this plan is a Piping & Instrumentation Diagram (or P&ID), you’d be best served to follow it to the exact letter (or symbol). Otherwise, you might end up finding some facility or maintenance manager that is of the same mindset as good ol’ Mike.

The Piping & Instrumentation Diagram is a great way to illustrate the layout of your complete system. Different symbols, created by ANSI or ISO, are used to identify the specific items in the diagram and lays out the entire system, installation, and process flow.

Air compressors are the heart of the pneumatic system and have a variety of different types of symbols that can be used based on the style of compressor that you have. Below are some examples of the symbols used to denote an air compressor on a P&ID:

On the left is a generic symbol that can be used for any style of compressor. Moving towards the right we have specific, unique symbols for each: centrifugal, diaphragm, piston, rotary, and screw compressors. As the 4th utility in any industrial environment, air compressors are a critical piece of equipment in the facility. From the compressor there will be a line drawn to denote the distribution system or piping that connects the supply side (air compressors) to the demand side.

On the demand side are a variety of different available symbols for each type of equipment. EXAIR recommends installing filters and regulators at the point-of-use to keep air clean and dry as well as operating at the minimal pressure for compressed air conservation. The symbols below are used for particulate filters, oil removal filters, and pressure regulators:

The symbols on the left denote the EXAIR products on the right: Automatic Drain Filter Separator, Oil Removal Filter, and Pressure Regulator

They’re laid out in this order for a reason which is why it’s important to follow the drawing exactly as shown when installing the equipment. The particulate filter must come before the coalescing filter in the supply line. Since we can experience pressure drop across filters, it makes the most sense to include the pressure regulator AFTER the air exits the particulate and oil removal filters for the most accurate representation of point-of-use line pressure.

Oftentimes, you may encounter a situation where the product you’re looking to use doesn’t have a specified ANSI or ISO symbol. In those cases, what is recommended is to choose any shape you wish and call it out specifically by name. For our Super Air Knives, this would look something like this:

Having a plan is one thing, but it’s important to make sure this plan has been well-thought-out prior to doing any installation work. It’s not that Mike Tyson is going to come around throwing haymakers or biting off ears if you don’t, but you run the risk of wasting quite a bit of time (and money!) by not adhering to the original plan.

If your plan includes using some of EXAIR’s Intelligent Compressed Air Products, give us a call. We have a variety of products ready to ship same-day from stock to help you get the most out of your compressed air system.

Tyler Daniel, CCASS

Application Engineer

E-mail: TylerDaniel@EXAIR.com

Twitter: @EXAIR_TD

Mike Tyson photo courtesy of Abelito Roldan via Flickr Creative Commons License