Electronics Protection - March/April 2012 - (Page 10)

Feature Enclosure Design: IVC’s New Lightweight Explosion-Proof Camera Enclosure System Clarke Esler, Marketing Director Industrial Video & Control For more than 10 years, Industrial Video and Control Company (IVC) has built a reputation on its ability to build specialized video cameras for use in harsh industrial environments. The company even introduced the industry’s first Class I Division 1 and Class I Division 2 rated dome pan/tilt/zoom (PTZ) cameras. IVC has designed and shipped cameras for use in the deserts of the Middle East, the jungles of South America, the North Slope of Alaska and marine environments worldwide. Because of this reputation, their experience in building equipment to meet recognized standards and their relationship with certification organizations like Factory Mutual, IVC was approached by a company to provide a camera for one their DoD customers. The requirement was for a PTZ camera with integrated LED illuminators that was to be used for the inspection of empty fuel tanks. The classification requirement was Class I Division 1. “At first blush, this seemed like a project that was right in our wheelhouse”, said Bill Richards, IVC’s vice president of Engineering. “However, the additional requirement that the unit had to be portable and weigh less than 25 pounds certainly presented IVC’s Standard Class I us with some challenges. To put this in Division 1 PTZ Camera perspective, our standard Class I Division 1 dome PTZ camera weighs in at over 100 pounds. Not something you’d want to carry in a backpack.” The camera Richards refers to is the IVC APTZ-3141-01, which is comprised of stainless steel dome that houses an auto zoom camera mounted on a pan tilt unit. This dome is connected to a heavy duty cast aluminum box that houses the unit’s power supply, IP encoder and fiber media converter. The challenge for IVC was to condense the functionality of their standard product, add integrated LED illuminators and package it all in a lightweight yet explosion proof enclosure. Richards called upon his experience as a naval architect and experience with lightweight composite materials. He also put together team of experts that included an optical expert who held several patents in LED technology, a physicist with experience in optics and mechanical packaging and Datum 3D, firm with expertise in 3D modeling, concept generation and mold flow analysis. flammable concentrations of gases or vapors is normally occurring. Additionally, areas are classified by the specific types of flammable gases or vapors that may be present. These are designated with a group number as follows: A: Acetylene, B: Hydrogen, etc., C: Ether, etc. D: Hydrocarbons, fuels, solvents, etc. IVC’s standard Class I Division 1 camera has been certified by Factory Mutual for use in areas with gas groups C and D. For this customer, the cameras will be used in and around various types of tanks that contain or have contained hydrocarbon fuels. Therefore, the likelihood of normally occurring flammable gases or vapors is high. This meant that the required division certification for this new camera was to be 1 and the group requirement Group D. For a piece of electrical equipment, such as this camera, the design criteria are very specific in order to pass Class I Division 1 certification. According to the US Department of Labor’s OSHA website these include: • Strength: The enclosure must be strong enough to contain an explosion within. The walls must be thick enough to withstand the internal strain. It has to be explosion-proof in case gas or vapors get inside. • Operating Temperature: The unit must function at a temperature below the ignition temperature of the surrounding atmosphere. • Flame Paths: The equipment must provide a way for any burning gases that may occur within the unit to escape from the device as they expand during an internal explosion; but, only after they have been cooled off and their flames “quenched.” • Ignition Containment: Any potential source of the ignition of gases or vapors present must be contained within the equipment. There are three ignition sources that are considered: 1. Arcs and sparks produced by the normal operation of equipment, like motor starters, contactors and switches, can ignite a hazardous location atmosphere. 2. The high temperatures of heat-producing equipment, such as lamps and lighting fixtures, can ignite flammable atmospheres if they exceed the ignition temperature of the hazardous material. 3. Electrical equipment failure is another way an explosion could be set off. A burn out of a lamp socket or shorting of a terminal could spark a real disaster in a hazardous location. The Solution Requirements The camera required by the end-user is to be used in areas that are classified Class I. This means the cameras will be used in areas in which flammable gases or vapors will or may be present in the air or on the ground in sufficient quantities to be explosive or ignitable. Some typical Class I locations are: • Petroleum refineries, and gas storage and dispensing areas • Dry cleaning plants where cleaning fluid vapors can be present • Spray finishing areas • Aircraft hangars and fuel servicing stations • Utility gas plants and operations involving storage and handling of liquefied petroleum gas or natural gas. The division number indicates whether or not the presence of 10 So Richards and his team set out to design a camera that would meet these requirements. The biggest challenge was going to be building a unit that was lightweight, yet strong enough to pass the rigorous certification testing that would measure the design against the criteria listed above. The material decision came first. Existing materials used by IVC for these types of camera enclosures such as stainless steel and cast aluminum were obviously not going to meet the weight requirements. One of the design partners first suggested titanium, but this was ruled out as it was determined titanium would not meet the explosion requirements. Based on his experience naval architect, Richards decided on carbon fiber. However, the final design is not entirely carbon fiber. The design team decided to use cast aluminum back plates for mounting internal components. The minor weight penalty was offset by the savings realized by the elimination of additional machining costs that would have been required if the unit were entirely carbon fiber. As pictured right, the IVC L-series camera design is comprised of a camera/illumination (lights and light control board) housing March/April 2012 www.ElectronicsProtectionMagazine.com http://www.ElectronicsProtectionMagazine.com

Table of Contents for the Digital Edition of Electronics Protection - March/April 2012

Electronics Protection - March/April 2012
Surge Stopper Shields Electronics From Transients Beyond 100 V
The Lowdown on IP Codes – Ingress Protection of Electrical Products
A Case for Safety - AC Arc Fault Circuit Interruption for PV Systems with Microinverters or AC Modules
Enclosure Design: IVC’s new Lightweight Explosion-Proof Camera Enclosure System
Portable Shock and Vibration Protection
Polycase Offers New Options for NEMA 4X Plastic Enclosures
New Circuit Board Shielding from Leader Tech
Laird Technologies Releases new Liquid Cooling Systems Product Line
ASI Releases New UL489 Hydraulic Magnetic Circuit Breakers
PEM C.A.P.S. Captive Panel Screws Offered in Three Mounting Styles26
SolarFocus Releases new SolarKindle Case
Indsutry News
Coherent Integrates Marway’s Power Distribution Solution into Energy Efficient, Direct-Diode Laser System Design

Electronics Protection - March/April 2012