Here is a position paper we wrote min the US. DOT doesn't have any prescriptive rules and it is up to individual companies to have a policy in place.
SHIELDED IGNITION
SCOPE:
Because our company, has a target of zero negative incidents, engineering proposes to address shielded ignition components as follows:
We have determined that it is an acceptable risk to systematically replace/install ignition components on all compressor units using a Risk Management approach in conjunction with following the applicable reference standards of, NFPA 37 and the Canadian Standard Association (CSA)
, as follows:
1. Risk management of ignition systems in use in remote unmanned facilities;
2. Use of Canadian Standards Association (CSA) (or equal) certified Class 1 Div 2 Group D components that do not void warranties from engine manufacturers;
3. and a phase in approach that replaces worn or defective components that are not certified Class 1 Div 2 Group D with components that are certified.
DISCUSSION:
The ignition systems on industrial gas spark engines are made up of the following parts:
1. The triggering system or control unit;
2. the control signal wires;
3. the coils;
4. the plug wires and/or leads;
5. and the spark plugs.
Most of the units we have in place have CSA registered Class 1 Div 2 group D Triggering Systems, control wires and to a lesser extent the coils. The plug wires, leads, and plugs are not rated, mainly because installation and maintenance procedures are what cause these elements to lose electrical integrity which may result in an uncontrolled ignition source; a flashover Note 1.
New engine designs and controls have allowed the industry to modify the installation and type of coils and leads. This change allows for a more readily available supply of coils and leads that include CSA certified parts. Class 1 Div 2 spark plugs are available, but a question arises on their use and warranty by the engine manufacturer. Lumen will inventory its use of CSA certified components and the availability of replacement parts.
SUMMARY:
The primary operational focus of our comapany is the health and safety of our employees and any other personnel working at our facilities.
The question of shielded ignition originated from the root cause investigation following a compressor fire a smaller Compressor Station. The action item suggested investigation into replacing the existing ignition systems with a shielded system. The shielded system would be one that meets the Class 1 Div 2 requirements. Other action items such as removal of building walls and the addition of gas detection systems at locations with overhead covers has been completed. These actions changed the engine locations from a Class 1 Div 1 to Div 2.
We are providing a safe work place through the following methods:
1. All operations personnel have been issued and are mandated to wear a personal gas detection device. 2. All operations personnel have been given extensive training on the hazards associated with their areas.
3. A Hot Work Permit program has been put in place and is actively being enforced both for Lumen employees and contract personnel.
4. Overhead structures have either been removed or walls have been removed or reduced in area to increase natural ventilation at locations with remaining overhead structures.
5. Permanent gas detection systems have been installed at all locations with overhead structures.
We believe that the risk of personal injury due to a fire caused from an ignition from the electric ignition system of a compressor unit is very small. We further state that a program pertaining to the systematic replacement of applicable components as discussed above would provide adequate safety assurances for personnel and equipment.
Based on all of the above, we recommend that the initially assigned priority of “2” for item number 6 be changed to a priority “3”.
Note 1: Flashover is when the voltage sent to the spark plug does not fire between the center and ground electrodes within the combustion chamber; instead, it shorts between the metal shell and the terminal nut on the plug exterior causing the engine to misfire. This can occur when the air is highly ionized (such as on a stormy day), or when the insulator is dirty. To reduce flashover NGK has ribbed corrugations on the top portions of the insulator.
