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Pepperl+Fuchs Blog

Easy Programming Features for Div. 2 / Zone 2 Purge Systems

Posted by Patricia Stafford on Fri, Jan 08, 2016

If you're considering a programmable purge unit, you may be wondering how easy it is to set up and configure it the way you want.

Before we take a look at the menu-driven features of our Bebco EPS 5500 series purge system for Div. 2 / Zone 2 applications, let’s go over some of the general aspects of purge protection.

Bebco EPS 5500 Purge UnitWhat is purge and pressurization and how does it work?

Purge and pressurization allows you to place general-purpose electric equipment in hazardous locations. With purge and pressurization, you can separate electrical devices from the surrounding hazardous atmosphere by placing the devices inside a lightweight enclosure. This enclosure is then purged with industrial-grade air or an inert gas, and maintained at a pressure higher than the dangerous external atmosphere, to prevent flammable gases, vapors, or dusts from coming in contact with the internal components.

What are the differences between automatic and manual systems?

Manual and fully automatic systems both provide the same level of protection. Depending on your needs and what kind of control over your process you are looking for, you may prefer one type of system over the other.

Manual systems

Manual systems are typically fully pneumatic. That said, you need to manually adjust the air flow to complete a successful purge cycle and reach the amount of pressurization in the enclosure required for safe operation. To adjust the airflow, you turn the pressure valve or regulator.

If pressure drops inside the enclosure, manual systems can trigger alarms, but you must monitor the application and manually adjust the regulator until you reach a safe pressure level again.

Fully automatic systems

  • Fully automatic systems are electronic control units with a menu-driven user interface. They are most commonly used with a solenoid valve or manifold.
  • Fully automatic systems allow you to set predefined minimum and maximum pressure levels. When these levels are reached, the control unit automatically activates the solenoid valve to increase or decrease air flow so the enclosure can return to safe operation.
  • Our fully automatic purge systems also allow for continuous temperature monitoring of the atmosphere inside the enclosure. You can set min/max temperature set points to energize the manifold to help dispense the hot air, or you can use these temperature set points to program an auxiliary output to activate a vortex cooler or AC unit.

What benefits do automatic systems provide?

  • They offer end users the confidence of having a reliable solution that provides continuous, 24/7 protection for electrical systems in hazardous locations.
  • They avoid unnecessary alarms or downtime due to loss of internal pressure of the enclosure that falls outside the minimum safe operating level.
  • They increase the lifespan of electrical components by maintaining safe temperature levels inside the enclosure.

Our 5500 series purge unit offers five preset programs that easily and quickly configure the system to operate in a variety of applications. These programs allow setup and operation of the unit without extensive technical knowledge or know-how.

1. Program 1 is designed for hazardous gas environments. This program offers manual operation for systems with a regulator, where the solution does not have an electric solenoid valve to operate under fully automatic conditions. Purging starts immediately, without needing to wait for the enclosure to reach a certain pressure value.

2. Program 2 is designed for hazardous gas environments. This program allows you to set min/max pressure values to activate the manifold or solenoid valve. Thus, you have a delayed purge—the purge cycle starts after the enclosure reaches the user-defined minimum pressure level. This program does not cut power when there is a total loss of pressure. Instead, when pressure falls below a certain point, an alarm goes off. The priority is machine availability. This program and Program 3 are the most commonly used programs.  

3. Program 3 is designed for hazardous gas environments. Like Program 2, this program allows you to set min/max pressure values. Again, you have a delayed purge—the purge cycle starts after the enclosure reaches the user-defined minimum pressure level.  However, along with setting off an alarm, this program cuts power when pressure falls below a certain point. The emphasis is on safety. This program and Program 2 are the most commonly used programs. 

4. Program 4 is designed for hazardous gas environments. This program, which enables continuous operation, immediately starts purging on power-up regardless of the initial pressure value. It is useful for applications involving such things as continuous flow, dilution processes, or gas analyzers. This program does not cut power to the application if there is a total loss of pressure, but does activate an alarm. The advantages of continuous operation include machine availability and efficiency. Possible disadvantages are that the generator runs harder and the process uses more air or gas. As a result, the process becomes more expensive in terms of the amount of gas and power consumed as well as wear and tear on the machinery.

5. Program 5 is designed strictly for combustible dust environments. No purge cycle is necessary. The user is required to clean out the enclosure to remove any dust or outside particles. This program does not cut power when there is a total loss of pressure, but does activate an alarm.

Questions about Purge Systems? Get the Engineer's Guide

 

Topics: Purge/ Pressurization Systems

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