The case for custom

A standard, off-the-shelf pressure sensor refers to one whose specification or build standard remains unchanged. A customised pressure sensor is based on a standard product but whose software or hardware has been modified so that it meets a specific requirement. For example, a customised pressure sensor might be a standard unit but fitted with a special subsea connector, high temperature electronics, a modified housing, or a specific communications interface.

But with such a huge selection available, no shortage of sensor suppliers and Internet search engines that provide a fast, easy method of comparing performance, price and availability, why would an engineer choose anything other than a standard ‘off-the shelf’ pressure sensor?

The most obvious reason to choose a custom pressure sensor is that there is no a standard ‘off-the-shelf’ sensor that meets the specification. Not every pressure sensing challenge can be solved with a standard sensor. It can often be more cost effective to outsource this to a third-party pressure sensor supplier with the necessary skills, experience and in-house engineering design services. Working from original or customer-supplied drawings, a reputable supplier can often create a robust, cost-optimised sensor that is fully in-house tested.

Contrary to popular belief, custom sensors are not necessarily just for unusual one-offs or small batches. They are often the most appropriate choice for higher volume, mainstream applications up to 10,000 pieces.

Sometimes, a standard sensor may incorporate hardware and functionality that is not required. This means overall unit costs may actually increase by purchasing standard off-the-shelf sensors rather than custom versions.

Below are some recent examples of custom designed pressure sensors from Impress Sensors & Systems for specific customer applications:

Transmitter with subsea series electrical connection

This product was designed to operate in applications where the external pressure applied on the housing and electrical connection could reach as high as 400 bar. Utilising a subsea series electrical connection and by hydrostatically testing the product to ensure it met these requirements, a suitable custom pressure sensor was developed.

Concrete slurry pumping

This stainless steel pressure sensor was designed to measure 12 bar of concrete slurry being pumped along a delivery line. In this application, there is a possibility that blockages can occur and pressures can reach as high as 200 bar. Therefore, the pressure sensor was custom designed to withstand this level of pressure without rupturing. Designed with an ANSI 1500 flange and secondary containment, the sensor design ensures a rugged failsafe solution. They are rated to IP67 to withstand the concrete piling conditions on site. The sensor is a unique, flush-mounted design with a special polyurethane protective cover on the diaphragm, which acts as an effective mechanical filter, to ensure that the aggregates in the concrete do not destroy the sensor element.

Remotely Operated Vehicle (ROV) – offshore

For this application, a highly accurate pressure sensor was custom engineered for an OEM manufacturer of ROV equipment used for geological surveys. The size constraints, accuracy and cost issues were all solved with an innovative design, whilst maintaining a very competitive price in an increasingly competitive market.

Leak control/data logging in the utility industry

The water industry is under constant pressure to reduce leaks in the water distribution system. A common method is to control the mains pressure by utilising data from portable battery-operated pressure loggers. Impress was tasked with designing a low power pressure transducer with an integral ‘quick-release’ fitting and static errors of better than 0.1%.

Low cost PCB-mountable pressure sensor

Electronic tyre pump control machines in petrol stations is a growing market. Impress Sensors designed a PCB-mountable device that accurately controls the pressure set by the user to stop the flow of air once the desired tyre pressure has been met. This device meets the most stringent requirements in terms of being very low cost but accurate.