Design-2-Part

How OEM's can make their parts better, faster, and more efficient.

Reinforced Plastics

Informed and impartial coverage on the global composites industry.

Metal 3D Printing Design Guide

Direct Metal Laser Sintering (DMLS) 3D printing for parts with reduced cost and little waste.

Chemical Engineering

The industry gateway for chemical engineering and plant operations.

more free magazines
Boyle's Law

Boyle's Law, proposed by Robert Boyle in 1662, states that for a closed isothermal (constant temperature) system, the product of the pressure (P) and volume (V) is a constant,

Equivalently, the product at two different states must be the same,

McLeod Gages
Suppose that initial pressure and volume in a McLeod Gage are given by,

P1 = Pi

V1 = V + A·h0

where V is the reservoir volume and A is the cross-sectional area of the sealed tube, as shown schematically below.

Suppose that the final compressed pressure and volume are given by,

P2 = Pgage

V2 = A·h

According to Boyle's law, we have,

For a typical manometer, . The unknown pressure Pi can be reduced to a function of the height difference h,

Furthermore, the volume of the reservoir is usually much larger than the tube,

V » A·(h0-h)

This allows us to drop the area term, resulting in a simple quadratic function for the pressure,