*an opinion about even one of the questions would be appreciated*
I have a question about heated molds in a Class 1 Div 1, Class 1 Zone 1 area(s).This is specific to fiberglass manufacturing where flammable resin (gelcoat) is being sprayed onto a mold. This process is very common and has been around for decades. Recently, there have been a number of new electric resistance heating technologies offered to embed into the molds. The purpose is to manufacture at consistent temperatures or to elevate temperature for curing. There are a number of questions related to this but ill be as brief as possible. I have done extensive research on this but I want to ask this on the forum to see if there are other views on this.
First, the molds are traditionally made of insulated products, i.e. polyester or vinyl ester resin and fiberglass fabrics. These would naturally insulate the mold electrically if you were to embed an exposed electrode and a resistance heater into the mold during construction. The resistance heater (one example) would be a thin veil fabric made of carbon fiber and the electrodes are made of copper. After these resistance heaters are laid in and covered by multiple layers of fiberglass and resin the mold will be put into service. The molds will average 16 sq/ft and will regularly see flammable liquids sprayed onto the surface in a class 1 Div 1 area.(Gelcoat, same material as the exterior of a boat) In this scenario I have a few questions:
1) If the heater is embedded, what standard is there to determine it is safe electrically from spark? A typical 1000V insulation test over the entire surface area is one method I am thinking of. This type of test is used for dielectric testing of heaters in standards such as UL 1278 and others. How could you apply an insulation test on 16q/ft surface that is 1/2" thick? Im envisioning covering the area with foil or wetting it down to perform the test.
2) Would a mold in this setting be required to be intrinsically safe? From all the reading I have done in the NEC, OSHA 1910.307 and NFPA 70E it would appear so.
3) Since molds are varied and different in shape and size from one to the next, would a standardized process of approved materials by the best approach here? In other words, and embedded heater can only be used if it is insulated with a minimum amount of resin and fiberglass fabric after being approved (Im thinking UL 746)
4) Can the temperature process controllers for the heater be located in a separate area and not require any special approval? A thermocouple and power cord can be run to the mold from a distance.
5) Since the molds are built by hand and therefore the heaters laid in by hand, what do you think is the best route to have the process standardized to be approved for use?
Any thoughts are appreciated..
I have a question about heated molds in a Class 1 Div 1, Class 1 Zone 1 area(s).This is specific to fiberglass manufacturing where flammable resin (gelcoat) is being sprayed onto a mold. This process is very common and has been around for decades. Recently, there have been a number of new electric resistance heating technologies offered to embed into the molds. The purpose is to manufacture at consistent temperatures or to elevate temperature for curing. There are a number of questions related to this but ill be as brief as possible. I have done extensive research on this but I want to ask this on the forum to see if there are other views on this.
First, the molds are traditionally made of insulated products, i.e. polyester or vinyl ester resin and fiberglass fabrics. These would naturally insulate the mold electrically if you were to embed an exposed electrode and a resistance heater into the mold during construction. The resistance heater (one example) would be a thin veil fabric made of carbon fiber and the electrodes are made of copper. After these resistance heaters are laid in and covered by multiple layers of fiberglass and resin the mold will be put into service. The molds will average 16 sq/ft and will regularly see flammable liquids sprayed onto the surface in a class 1 Div 1 area.(Gelcoat, same material as the exterior of a boat) In this scenario I have a few questions:
1) If the heater is embedded, what standard is there to determine it is safe electrically from spark? A typical 1000V insulation test over the entire surface area is one method I am thinking of. This type of test is used for dielectric testing of heaters in standards such as UL 1278 and others. How could you apply an insulation test on 16q/ft surface that is 1/2" thick? Im envisioning covering the area with foil or wetting it down to perform the test.
2) Would a mold in this setting be required to be intrinsically safe? From all the reading I have done in the NEC, OSHA 1910.307 and NFPA 70E it would appear so.
3) Since molds are varied and different in shape and size from one to the next, would a standardized process of approved materials by the best approach here? In other words, and embedded heater can only be used if it is insulated with a minimum amount of resin and fiberglass fabric after being approved (Im thinking UL 746)
4) Can the temperature process controllers for the heater be located in a separate area and not require any special approval? A thermocouple and power cord can be run to the mold from a distance.
5) Since the molds are built by hand and therefore the heaters laid in by hand, what do you think is the best route to have the process standardized to be approved for use?
Any thoughts are appreciated..
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