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# Air Cylinder Calculator

Enter the pressure and the force needed to move your prop, and get the size of the air cylinder needed. Use the next larger size air cylinder specfied to ensure you'll get the force you need.

Cylinder Bore Size Calculator
 Availabe Pressure: PSI Force Required: Pounds Safety Factor:
 Area Required: Square Inches Cylinder Bore Size: Inches
Air Valve Sizing Calculator
 Available Air Pressure: PSI Cylinder Bore: Inches Stroke Length: Stroke Inches Time for Stroke: Number of Cylinders: Seconds
 Volume Required: Cubic Inches Cubic Feet per Minute: Coefficient of Flow: CFM Cv (with 2 psi pressure drop) Cv (with 5 psi pressure drop) Cv (with 10 psi pressure drop)

### Estimate Your Compressor Size!

You can estimate the size of a compressor needed for your entire system by using the calculator (above) and 'backing into' the estimate!

• Using the Solenoid Air Valve Sizing Calculator on the right, enter your system pressure into the 'available air pressure'.
• If you're using the same size cylinders everywhere, use that number in 'cylinder bore'; if you're using a range of cylinder sizes, use your judgement for an average size estimate. Or, use math! Add up all the bore sizes, then divide by the number of cylinders.
• The same applies for the stroke length entry, estimate the average stroke for all the cylinders.
• Use 2 or 3 for the 'time for stroke' entry - watch how changing the speed by a second affects the CFM!
• Add up the number of air cylinders and put that into 'number of cylinders'.
• Click on 'calculate'.

The 'Cubic Feet per Minute' (CFM) is the maximum flow you're compressor will need to deliver to your system if all the air cylinders were triggered at the same time. This is rarely the case in haunting, so you can start reducing this number in a couple of ways.

First, since its rare that all the props will ever trigger at the same time, you can reduce this number by estimating the percentage of props that trigger at the same time. The table below is a rough guide to reducing the CFM.

 # Props Multiply CFM by: All 1 70% .9 50% .7 30% .5 10% .3 > 10% .2

For example, if your total CFM was 14, and half of your props are likely to trigger at the same time, the calculation would be

14 * .7 = 9.8 cfm (round up to 10 cfm)

A 10 CFM compressor would be a good size to reliabily supply air to this system.

### Tank Size is Important!

Another factor to consider when estimating your compressor size is the tank size. A larger tank helps short-term CFM, which is important to haunters. During an evening of screams, props will trigger in 'groups' or 'waves', where you'll have lots of them triggering for a short while, then just a few, then lots again. This has to do with how people move through your haunt. The compressor will kick in to recharge the tank during the peaks, and rest as the tank supplies air for the slow periods. This gives time for the compressor to rest and cool down. In short, get the largest tank that makes sense for your haunt, it'll help by reducing the total time your compressor runs.

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