It's a device that controls air pressure with a variable electrical signal (current or voltage). Those controlled by current, usually 4-20 mA, are called I/P (pronounced "I to P") transducers. Voltage units, E/P ("E to P") transducers generally use a 0-5 or   0-10 volt control signal. With a 4 mA signal you get the lowest rated output and 20 mA gives you the maximum output. The output is proportional for everything in between.

It depends on the application. Most automated systems use a PLC (Programmable Logic Controller) set up for the job at hand. There are multi-meters and calibrating meters available from a number of companies. A power supply connected to a potentiometer or rheostat will also give you a variable signal.

Almost all of our transducers are loop driven. This means that the variable control signal provides all of the operating power required. This is also referred to as a two wire system. Only the E/P versions of the T900 require a separate power supply (10 to 30 volts DC).

Generally you always want to use the narrowest range possible for your application. This will provide the greatest accuracy. You will also have to decide if you need to regulate down to zero psi or not.

Our transducers will always fail closed (minimum output) with the loss of power when used in the direct mode. The Type 500 and 550 will fail open (maximum output) when set up as reverse acting.

The Type 500 is best for most valve automation projects and is a good starting place for most general purpose applications. Use the T900 for situations that require high accuracy (it's accurate to within hundredths of a psi!) or if vibration and position changes are a problem. The T550 is similar in design to the T500 except in a smaller housing. Use it for densely packed applications. It also offers some pressure output options not available in other models. The T950 is based on the design of the T900 and is for explosion-proof situations.

Even though we calibrate the I/P's here before they're shipped, it's a mechanical adjustment that can shift when bumped during shipping. Supply pressure and the position it's in can effect the output of the T500 and 550. T900's and 950's usually do not have to be calibrated unless you want to tweak the performance to the highest degree possible.

Always put a filter regulator in the air supply in front of an I/P. It will stabilize the supply pressure and protect the transducer from contaminants, thus prolonging its life expectancy. These devices can be mounted in any position, but the T500 and 550 must be calibrated in the same orientation that they're being used. Generally speaking they'll work best upright (pneumatic ports at the bottom). The T900 and 950 can be mounted in any position without effecting calibration.


It depends on your application. Knowing your flow, accuracy and size requirements is the first place to start. The Type 90, 100 and 700 are the most accurate. The T800 and 850 are the smallest. The T90 offers a great combination of small size and high accuracy. A T400 is in the middle price and accuracy wise, but has low relief capabilities. The ½” versions of the 330 and 340 will flow at a high rate with moderate accuracy. There is a high relieving version of the T100 with an incredible relief capacity. This can be important when controlling air cylinders. The T700 will flow a larger volume of air than most of the others with excellent precision. Filter regulators will clean particles out of the air to protect downstream components. Stainless steel versions are also available. If you have any questions please contact us at the factory. We would enjoy talking to you about your application.

The accuracy of a regulator is a difficult concept to measure. It can’t be stated as a percentage the way a gauge can, or even calibrated to a particular reference standard. We use the term sensitivity. This refers to the smallest change in downstream pressure that the regulator can recognize and react to. This does not mean that the regulator is capable of holding a pressure to that degree. Other companies also use this same reference standard; unfortunately you cannot always compare these figures between companies.

There are two schools of thought. If you need to control pressure at 15 psi, then using a 0-30 psi range allows you to use the regulator at the midpoint of the range spring. This allows the spring to operate at its optimum efficiency. However if you know that the flow rate is likely to vary, then using a 0-15 psi range will limit the effects of droop, therefore making the regulator more accurate.

Droop is a naturally occurring phenomenon where a regulator’s output set pressure will start to drop as the volume of air passing through the regulator increases. Conversely if the regulator was set flowing at a high level and the volume is reduced, the set pressure will rise. ControlAir incorporates a number of design features in order to minimize this effect. It has virtually been eliminated in the Type 90 and 100.

Air consumption is the total volume of gas lost to atmosphere. Other than minute amounts that seep through various seals, precision regulators use gas to increase their accuracy. The exact amount will vary (even within the same model) and is often much lower than the quoted spec. This is sometimes referred to as “bleeding”. This could be important if you’re using something other than compressed air or are using a large number of regulators.

The T700 is a traditional regulator design that takes a higher air pressure and allows you to accurately control it to something lower. If the downstream pressure should rise, then it will sense this and vent air until the set pressure is re-established. The 700BP will only perform the relief functions. If the pressure upstream of the regulator exceeds the set point, then it will vent air until the pressure drops below the set point. In essence it is a precision variable relief valve.

The 700BP is capable of exhausting air at a rate of up to 50 scfm while the 700 can only vent at 4 scfm. The 700BP can also serve as a fail-safe device that can divert air to a valve if the air pressure climbs above a certain point.

Yes, but please contact the factory to confirm compatibility. We may even have special customized versions specifically designed for that gas. Often the largest concern is containing the gas that escapes from the regulator.

Other than the trace amounts that seep through the various seals everything is channeled out the exhaust port. Most of our regulators have an option for a tapped exhaust that would allow you to pipe it away or recapture it. On relieving regulators, this port must be open to atmosphere.

If downstream pressure increases a relieving regulator will sense that increase and vent air in order to maintain the set pressure. A non-relieving regulator can’t do that. However it will not leak gas to the atmosphere the way a relieving regulator will. This can be important if the regulator is controlling an expensive or dangerous gas. A non-relieving regulator will not leak or “bleed” during normal operation. For safety reasons you should only use a non-relieving regulator in a constant flow application. If the regulator is left dead ended, the downstream pressure will eventually climb to whatever the supply pressure is.

No. The regulator will start to vent gas the instant it climbs above the set pressure. However, it won’t vent at its maximum rate until the downstream pressure is about 5 psi above the set point.

Absolutely. Even though this regulator has the ability to flow a large amount of air, it will work well in low flow or dead-ended situations.

That depends on your application. Do you need a gauge, mounting bracket, different knob or tamper proof cover? If you’re concerned about leaking gas, most of our regulators are available with a tapped exhaust or with a non-relieving option. The T700 even has different versions to control the bleed rate.

An optional “L” shaped bracket is available for almost all of our regulators. Most of our regulators also have the ability to be panel mounted so that only the knob and adjustment stem are visible. The regulator may not come with the nuts required to do this, or the nut might be optional. Please remember that the drain valve on filter regulators must be facing down in order to drain properly.

In its simplest form, a relay uses a variable air pressure signal instead of an adjustable knob to control output pressure. Relays also have the ability to tailor the signal with bias adjustments and improve the volume capacity. Our Mite series of snap acting relays are designed to switch, lock or vent various ports based on an increasing or decreasing signal. These devices are used in safety controls as fail-safe protection.

A T200 provides a linear change that can be adjusted to either add or subtract up to 30 psi from the incoming signal pressure. It can also be adjusted so that there isn’t a bias change. The T600 is ordered with a preset ratio that will multiply the incoming signal by a factor of one, three or six. With a 1:2 ratio a 3-15 psi signal becomes a 6-30 psi output.

It will deduct about four psi from the incoming signal. This is often used to convert a 3-15 psi signal from a transducer (a common application in valve automation) into a 0-15 psi signal. Please note that the transducer would have to be recalibrated to reset the 15 psi upper range.

No. This device will not create pressure or air volume by itself. You must have at least 120 psi existing someplace else and connected to the relay in order to obtain an output pressure or flow rate that high.

No. This device will not create pressure or air volume by itself. You must have at least 120 psi existing someplace else and connected to the relay in order to obtain an output pressure or flow rate that high.