Posted to News on 18th Aug 2007, 21:16
Rugged pressure transducer never needs recalibrating
Gems Sensors & Controls is launching the 3100 series of thin-film metal pressure transducers that offer very high stability, thereby reducing downtime and saving engineering resource. The unit features a very small package size, as little as 25mm in length, which is said to be significantly smaller than other sensors. This, in turn, allows OEMs to reduce the size of their own products.
The stainless steel sensor of the 3100 is welded to a pressure port using a gas laser welding technique that gives a high-strength, fatigue-free joint. Both components of this simple two-piece construction are manufactured from high-strength precipitation-hardened stainless steel, ensuring a durable construction and mechanical integrity. The thin-film gauges are deposited on to the diaphragm surface using sputtering techniques, which helps to eliminate drift and ensure repeatable performance. As a result, long-term stability is believed to be three to four times better than transducers that are based on traditional technology.
Long-term drift for the series is 0.1 per cent of full scale per year non-cumulative. This eliminates recalibration, which can be required every 6-12 months on other sensor types, taking up to 30 minutes per sensor. This saving in downtime and engineering resource can be significant when added to the cost of the unit. The all-welded construction also eliminates leakages that can occur on sensors equipped with O-ring seals, and means that the sensor itself is very robust.
Wide choice of pressure ranges
The 3100 covers a very broad pressure range, from 10 up to as high as 2200bar. This means that manufacturers can use the same model type for different applications. For example, medical gas distribution measures bottle pressure at 250bar and line pressure at 16bar. Both ranges are available in the 3100 series with the same accuracy and stability.
Operating temperatures for the units can be as high as 135degC, making the 3100 very cost-effective for high-temperature applications.
The thin-film gauges are electrically isolated from the diaphragm surface by a layer of silicon dioxide, while the sensing element is wire bonded to the PCB by aluminium wire with a bond strength not less than 150 grams, offering the benefit of improved cyclic pressure reliability. The unit is constructed with a single PCB, which also incorporates filtering and transient suppression components. This provides both a high level of RFI protection and resistance to voltage spikes.
3100 sensors are available with a choice of six electrical connections and nine pressure ports, which means that the unit is suitable for most applications without modification. In many cases existing sensors can be replaced without any need for re-engineering.
Within the range, the 3200 heavy-duty pressure transmitter features a thicker diaphragm, and a pressure snubber - a small orifice that directs pressure away from the sensor surface, thereby enabling the unit to withstand the rigours of cavitation or extreme pressure spikes. This feature is very important in mobile hydraulics.
