IES Blog

Simply put, if you only need reasonable (~5%) accuracy and a visual indicator, there are many relatively inexpensive volumetric flow measurement instruments, such as those offered by Kobold USA (contact us for help).  However, because gas volume is significantly effected by temperature and pressure, if your application calls for higher accuracy you should be looking at an instrument that measures mass flow.  

The momentum transfer pump category is comprised of Turbomolecular Pumps ("Turbopumps") and Diffusion Pumps.  

Entrapment (or Capture) Pumps are comprised of two primary types types:
cryopumps and ion pumps.

The Positive Displacement Pump category is comprised of rotary vane, piston, roots, scroll and diaphragm pumps.

The Watlow F4 temperature control module was introduced in 1999 as a high end workhorse instrument.  It is a very powerful, feature packed, easy to program controller with a back-lit LED display that allows the user to access the controls manual from the front panel.  

With their obvious cost and size advantages, why would you not use a Watlow Firerod cartridge immersion heater instead of a screw plug immersion heater to heat water? 

To determine the most appropriate vacuum pumping system for your application, it's important to know what types of vacuum pumps are available, what are their capabilities, and how they are different.  In the high technology vacuum world there are three fundamental types of pumps: Positive Displacement, Momentum Transfer and Entrapment.

In Part 1, we discussed the fact that moving molecules in a vacuum is different than moving air at atmospheric pressure.  As the air is pumped out of a vacuum chamber, the flow characteristics change from laminar flow, whereby most of the molecules are moving in the same direction (towards the pump), to molecular flow, whereby molecules are moving randomly.    

It may seem a simple matter to hook up a vacuum pump to a vacuum chamber and remove the air.  Some days the chamber achieves the desired vacuum pressure in a short time and other days it takes much longer.  Why the difference?

To properly design a vacuum pumping system, it helps to have a full understanding of the concept of moving gas through the connecting tubing between the chamber and the vacuum pump.  The real issue is, as the pressure in the system is reduced, gas molecules are more difficult to extract due to the principal of conductance.