Tag Archives: differential pressure

Differential Pressure Transducer

What to Look for in Durable Differential Pressure Transducers?

At Validyne Engineering, we have almost half a century in the industry, providing a range of different low cost, highly accurate pressure sensors for many different industries and applications. Over time, we have provided these sensors to various industries and companies. We have also listened to the needs of our customers to develop the sensors, transducers and transducers to get the job done.

One of the most important aspects of our devices is quality. We produce a durable, rugged line of differential pressure transducers. We believe we have a top selection of these transducers for all industries and applications.

The Validyne Difference

All of our differential pressure transducers are designed to meet performance specifications in highly demanding environments. Most of the transducers we sell can be used for both liquids and gases. They have been extensively used in the field with test vehicles and aircraft as well as in all types of environmental conditions.

Our in-house team of designers and engineers, all with extensive experience in sensor component development and design, has the ability to incorporate the needs of our customers into specialized solutions for their applications. We are also able to take this knowledge and design transducers for general use that are superior to other designs on the market today.

Up to the Test

One of the biggest complaints we hear from people looking for transducers is their inability to survive difficult working conditions. Each of our components has been thoroughly tested to provide our end-users with the quality part to stand up to real-world use. We also provide support and assistance in helping you to choose the right component for any application.

Our transducers are able to handle changes in the environmental and ambient temperatures with minimal impact on the accuracy of the pressure readings. They are designed to provide precise readings with fast response, giving test engineers the data they require. Fully compatible with data management systems, they are easy to integrate into field or laboratory testing situations or where and as they are needed.

Easy to mount with pre-drilled holes, they have a small, compact size and low weight make these differential pressure transducers the right component for the job. They are able to stand up to spray and moisture and also capable of wet-wet operations. Our transducers are available in differential or absolute pressure, as well as the option for a CE approved model if so required.

Measuring Vacuum Pressures

A subject that tends to cause confusion when specifying pressure transducers is the  measurement of a vacuum and how it relates to absolute pressure.

Here are some definitions:

Absolute Pressure – A pressure referenced to zero absolute pressure.

Gauge Pressure – A pressure referenced to the local atmospheric pressure

Differential Pressure – The difference in pressure between two points.

Vacuum – A pressure less than the local atmospheric pressure.

From the above definitions we can see that an absolute pressure is measured starting from absolute zero – the complete absence of pressure. The complete absence of pressure exists in space, but on the surface of the earth the atmosphere exerts a pressure of about 14.7 psia at sea level. A barometer is a device that uses a column of mercury to measure the atmospheric pressure and this ranges from about 27 In Hg to 33 In Hg, depending on the weather. In addition to varying with the weather, the local atmospheric pressure also depends on elevation. The atmospheric pressure is about half that at sea level when you are at an altitude of 17,000 feet.

A vacuum is any pressure less than the local atmospheric pressure. It is defined as the difference between the local atmospheric pressure and the point of measurement. A vacuum is correctly measured with a differential pressure transducer that has one port open to atmosphere. If, for example, the negative port is connected to a vacuum and the + port open to atmosphere, the transducer signal will increase as the vacuum increases. It will always indicate the correct vacuum, even when the local atmospheric pressure changes with the weather.

An absolute pressure transducer cannot measure vacuum directly. If connected to a vacuum the signal from an absolute pressure transducer will decrease as the vacuum increases, but you can only know the actual vacuum if you know the local atmospheric pressure because vacuum is always referred to the atmosphere. Another way of thinking of a vacuum is that it is a negative gauge pressure.

The local elevation will affect a vacuum measurement because the atmospheric pressure is affected: no matter how powerful your vacuum pump, you cannot pull a vacuum of 14 psi at an elevation of 6000 feet – because the atmosphere there is only about 12.5 psia and the difference between the atmosphere and a vacuum cannot exceed that pressure.

In summary: a vacuum is best measured with a differential pressure transducer having one port open to atmosphere.

Check out Validyne’s absolute, vacuum, gauge and differential pressure transducers.

measuring vacuum