I/P Converter and E/P Converter In Full Explanation

What is an I/P Converter?

I/P converter is a type of electro-pneumatic regulator. I denotes electric current, and P denotes pneumatic pressure. It is also known as a proportional I/P transducer. Simply speaking, it converts electric current signal to pneumatic pressure, with an important characteristic of being positive proportional. As current is tuned up, the output pressure also increases proportionally. There are two main types of converter on the market, they are I/P converter and E/P converter. I/P converter converts DC direct current signal to pneumatic pressure and an E/P converter converts a voltage signal to pneumatic pressure. I/P most commonly receives a 4-20 mA signal, and E/P takes 0-10V input signal.

What type of I/P or E/P converter does KaoLu offer?

Please refer to our selections below and click on the product that suits your pressure requirements.

KaoLu offers I/P and E/P converter with wide controllable pneumatic pressure output. For our products series, it is necessary to provide a 24VDc power supply. Let’s look at our three standard product series:

  1. QKL-B1T/B3 – available in the 0 – 8 bar (0 – 116 psi) adjustable range.
  2. QKL-B1S / B3H – available from 0 – 30 bar (0-435 psi) adjustable range. Customizable pressure range is possible with up to 3500 L/min of flow.
  3. QKL-B4H – available up to 70 bar (1,015 psi)

All models comes with either 0-10V or 4-20mA command signal. What’s more, we also offer digital signal option that allows you to control output pressure via RS485 modbus. Customizable pressure range is also possible. Our I/P or E/P transducers allows a great flexibility for our user such that it Is possible to pair our converter with a volume booster when a large flow rate is required, with an external pressure transducer, or even with a pressure booster. For example, our QKL-B3H currently offers a flow rate up to 3500 LPM or 123 scfm, when a QKL-B1T is paired with a volume booster, it is possible to offer up to 7000 LPM or 246 scfm. Our I/P converter has been used in a variety of industry, ranging from web tension control, chemical-mechanical polishing, glass polishing, calendar equipment…etc

Please check our youtube channel for further interesting application with our I/P and E/P transducer.


Working Principle of I/P Converter

I/P Converter works in a similar principle to a flow proportional valve. Both products are based on electromagnetic force balance principle to control flow rates. However, with different mechanical structures, I/P converter converts electrical current to output pressure, proportionally, and a flow proportional valve converts electrical current to output flow rate, also proportionally. With an I/P converter, EM (electromagnetic) theory is taken into consideration, which allows the buildup of current that results in mechanical actuation of the transducer, thus pressure ouput. KaoLu offers both types of converter, flow control and pressure control.

For flow proportional valve products, please visit our catalogue:


For  I/P converter products, please visit website:


When should I use a I/P or E/P converter?

Three main application areas where they are used:

  1. Tension control such as during the moving of material, especially during transportation of paper, film cable and textile.
  2. Winding-based machines, such as pricing machine, extrusion machine, coating or laminating machines.
  3. Dancer roll system, when applying load force to dancer
Hanky Printing Machine

What should you consider when purchasing a I/P converter or E/P converter?

You should consider 3 main factors
1. What pressure range
2. What type of command signa
3. How proportional is the output pressure to the command signal

First, KaoLu offers I/P, E/P converter with controllable pressure up to 1,015 psi (70 bar). With this range we are capable of customizing the pressure range if you decide to use a 0 500 psi, that corresponds to 0 10 VDc. Next, you have to check what digital command signal fits your system. We are currently offering 0-10VDc, 4-20mA, or RS485 modbus selections. The converter also comes with a feedback signal which you could read to know the outlet port pressure. Apart from the control side, it is important to know the performance of the regulator, i.e. how proportional it is to the command signal.

This refers to some important parameters: accuracy, repeatability, linearity, resolution, and even flow rate. Please refer to our specific product specification to understand our capability.