1. Class 1, Div 2 Corrosion Transmitters
2. Switching large power loads with Type X Purge
3. Troubleshooting the Type X Purge
4. OEM Application Note
1.CorrTran™ Corrosion Detection Transmitters Now Available for Class I, Division 2 Hazardous Location Mounting
Pepperl+Fuchs’ innovative CorrTran Corrosion Detection Transmitters now satisfy Class I, Division 2 hazardous location applications. CorrTran transmitters allow users to monitor online the effectiveness of their corrosion inhibitors, and to detect and correct corrosion issues through upkeep and preventive maintenance before they become a costly problem.
Their low-power design allows mounting directly within a Division 2 hazardous location. In this configuration, the control signal (4-20 mA circuit) must be connected in accordance with the National Electrical Code according to Division 2 wiring methods. Division 2 locations are considered hazardous only under abnormal conditions, such as a faulty valve, unexpected release, or aging seal, among others.
These rugged transmitters feature a two-wire loop powered 4-20mA signal with HART protocol for accurate real-time monitoring. Through these signals, general corrosion or pitting of pipe or vessels can be detected. A variety of probe styles and materials of construction are also available to satisfy most any application requirement.
Visit CorrTran online for more information.
2. Switching large power loads with Type X Systems
Chris Romano, Product Manager
Reasons why Purging/Pressurization is so effective:
- The method allows power requirements greater than what intrinsic safety allows.
- Standard enclosures can be used. Large explosion proof enclosures are heavy, expensive and usually have a long delivery date for any modifications.
Type X systems require connecting and disconnecting of power to the pressurized enclosure when the pressure within the enclosure is above or below acceptable values. Pepperl+Fuchs Type X 2000 and 4000 series has two normally open contacts for connecting and disconnecting power to the pressurized enclosure. The contacts are located inside the explosion proof enclosure that houses electronics for these units, and can be used on single phase, up to 220VAC, 10amps for 4000 series and 20amps for 2000 series. The power requirements noted are for the pressurized enclosure, not the explosion proof one.
Sometimes the power requirement within the pressurized enclosure requires higher amperage, voltages, 3-phase power, or some combination of these items. Here, the contacts of the Type X System can not be used to connect and disconnect the power.
The reason the contacts do not switch higher loads or three-phase is that the contacts are from a PCB mounted relay that is mounted inside the explosion proof enclosure along with other electronic equipment.
The higher load requirements usually produce an arc on the contacts and EMI noise could affect the electronic components and operation. Also, these contacts should be protected with some type of thermal or other technology for overloads on the systems (ex.- motor windings can fail and draw excess current. If not protected, it can burn up the contacts and/or the motor).
The solution to this power requirement is to use the contacts from the Pepperl+Fuchs purging/pressurization system to energize a separate contactor that can handle the load requirements for the pressurized enclosure. These contactors usually operate within the limits of the contacts on the Type X units and are specifically designed for the application and load requirements.
At this point, you are probably wondering, "where can I put this separate contactor?"
Do NOT put it inside the pressurized enclosure because there will always be power on the one side of the contactor. There can not be any power inside the pressurized enclosure during or before purging (per NFPA 496). The contactor has to be placed in a safe area, which can be in the control room or a separate explosion proof enclosure.
The location of the contactor in these areas allows you to to service the contactor without affecting the Pepperl+Fuchs Type X system. This approach isolates higher current away from the delicate electronics of the Type X system, and since these contactors are small in design, the cost for the explosion proof enclosure is kept to a modest level.
To sum it up, Pepperl+Fuchs' Type X System allows you to use standard enclosures and switch large power loads. Use a separate contactor housed in a small explosion proof enclosure to meet NFPA standards and keep your application and equipment safe.
The most important advantage in this approach is that you can choose the specific contactor for your application, therefore providing the best solution for your system.
Note: NFPA 496 - Standard for Purged and Pressurized Enclosures for Electrical Equipment.
Learn more about Type X Purge Systems.
3. Basic troubleshooting for X-type Purge Systems
Arthur Shvartsman, Applications Engineer
As a first step in understanding Pepperl+Fuchs' Type X Purge System, it's a good idea to know the differences between the 2000 and 4000 series. In the 2000 series, the flow rate is measured by pressure within the enclosure. The 4000 system measures the flow through the vent (the outlet), as required by the new ATEX directive.
Examples below outline the most common 'symptoms' associated with each system:
4000 Series
Symptom: With all the lines checked and the incoming pressure reading normal (around 60psi) the system cycles between the rapid exchange and safe pressure.
Cause: Even though the pressure is sufficient on the inlet, the sensor in the vent is not measuring sufficient flow because not enough airflow gets to the vent. This is usually caused by leaks through cabinet seals or the conduits through which most of the air/gas escapes before reaching the vent.
Cure: Tighten the enclosure and seal the leaks in conduits.
2000 Series
Symptom: The system works fine when the glass cover is not installed and stops working when it’s installed.
Cause: The conduit that connects electrical wiring from the relays in the 2000 system to the pressurized enclosure is not poured or sealed properly. The pressure inside the explosion proof housing becomes equalized with the purged cabinet. The differential pressure switch inside the X-purge system does not detect the difference in pressure.
Cure: Seal the electrical conduits.
4. OEM selects Pepperl+Fuchs as Preferred Vendor
Jeff Hanson, District Manager
An OEM manufacturer of production equipment for pharmaceutical, specialty chemical and specialty food products came to Pepperl+Fuchs for help on a hazardous location project.
Typical applications for the OEM included batch mixing systems for pharmaceutical and specialty chemical products, size reduction systems for wet or dry milling and fluid bed systems for drying, granulating and coating. These systems are typically installed in a Class 1, Div. 1 Hazardous area.
The OEM was using a BebcoEPS 4003 Type X Purging System to protect a control panel. They were anxious to resolve a communication problem between a Zener barrier and a temperature transmitter. Pepperl+Fuchs sent the OEM a KFD2-UT-EX1, (Universal Temperature Module), with programming cable and instructions on how to download and use the PACTware configuration software.
This corrected the problem, and enabled them to complete their final acceptance test and make a critical shipment on schedule. As a result of this positive experience, the customer gave Pepperl+Fuchs all the model numbers of intrinsically safe barriers that they had used over the past 18 months to cross to Pepperl+Fuchs barriers, and we are now the preferred vendor for all of Purging/Pressurization, and Intrinsic Safety requirements.
Pepperl+Fuchs, Inc. 1600
Enterprise Parkway, Twinsburg, Ohio 44087
Phone: 330-425-3555 Fax: 330-425-4607
www.am.pepperl-fuchs.com