Air pressure measured by?

Question

list six diffenent ways of stating air pressure and give the standard sea level equivalent for each.

Answer 1

Units of pressure common to measuring air are:

Inches of mercury (29.92 = atmospheric at sea level)
Inches of water (406.76 = atmospheric at sea level)
Millibars (1013.25 = atmospheric at sea level)
kiloPascals (101.325 = atmospheric at sea level)
Pounds-per-square-inch (14.695 = atmospheric at sea level)
Atmospheres (1 = atmospheric pressure at seal level)

Answer 2

By far, the most accurate way to measure air flow is to count individual molecules. To make this measurement more manageable, the molecules are measured by the box full. The box size is a standard cubic foot (12" x 12" x 12"), measured at sea level (a point of standard atmospheric pressure). The amount of standard cubic feet consumed is measured either per hour or per day. This measurement lets you measure high consumption rates (air dryer output) or relatively low consumption (air flow into a cable) in a meaningful way, using Standard Cubic Feet per Day (SCFD) or Standard Cubic Feet per Hour (SCFH). These measurements help in monitoring for system leaks and in cable maintenance.

Because of maintenance activity, cable splices, and the use of pneumatic fittings along the cable route, all cables tend to leak to some extent. For this reason, an allowable air flow rate, called Optimum Air Usage (OAU) has been established. OAU is the calculated air consumption rate that an air pressure system should use under normal operating conditions. It is based on a consumption rate of 1.25 SCFH per sheath mile of cable.

Like the minimum air pressure standards, OAU is important in dispatching maintenance technicians. A flow increase at an air source is not valuable information unless you also know the OAU, or what the air source should be flowing. OAU is also important in the design of an air pressure system and for evaluating system quality.