Propylene Oxide is a highly reactive chemical that is used to make polyurethane (in its base form), propylene glycol, and propylene glycol ethers to name a few. Propylene glycol is probably the most widely known resultant of propylene oxide. Propylene Glycol is used in most car’s cooling systems and even fruit flavored liquids you squirt into your water bottles. Another final product of P.O. is polyurethane, which is used in common products we see and use every day. Polyurethane makes up products such as rigid foam like you see in the thermal insulation of your home, flexible foam cushions for seats and furniture, even foam mattresses. Some of the lesser known products made with propylene oxide are flame retardants, lubricants for oil field drilling, the mid & outer soles of shoes and synthetic lubricants.
For propylene oxide service, our cooling equipment must typically be installed into a Class 1, Division 2, Group B area. We talked about area classifications in an earlier blog post, but we will give you the short version for this particular fluid. Class 1 means that flammable vapors and gases may be present. Division 2 states that there is an ignitable concentration of fluid that is being handled or processed but that this fluid is in a closed system or container. There can be an actual rupture or breakdown of the system under some conditions. There are four liquids that fall into the Group B classification: Hydrogen, Butadiene, Ethylene Oxide, and Propylene Oxide. One important note is that if a piece of equipment is approved for Group B classification, it is also approved for Groups C and D. Class A is the most stringent classification for equipment.
In 2015, Smart Family of Cooling Products has provided three propylene oxide chillers for various applications. All of these involved maintaining temperature during some sort of the transportation process: Storage, actual transporting of the product, and off-loading. During off-loading, the fluid temperature is most critical. At all times during this process, the propylene oxide temperature must remain below 80F. If it rises above that, you risk reaching the flash point. That would have a disastrous effect. To allow for some safety, we designed around a fluid temperature being maintained at 68F.
The three units we built in 2015 were all capable of directly cooling the propylene oxide fluid through an all 316 stainless steel DX evaporator. While most manufacturers would require a secondary heat exchanger to achieve their fluid cooling, we were able to handle it directly. Much of this is attributed to our ability and willingness to manufacture custom refrigeration equipment. The reduction in piping and connections, greatly reduces the chance for leaks, which is critical when dealing with a highly flammable fluid.
The sizes for the propylene oxide chillers we built ranged from our SSCD060 to the SSCD300. Special care was taken in designing the electrical system so that anything that would generate heat was operating well below the ignition temperature of the fluid. One of the most critical items was the crankcase heater on the compressor, which under normal operating conditions would exceed this value.
In addition to the cooling of the critical fluid, the explosion-proof construction, the units were all located in coastal area or directly on the coastline. Because of their installation, the chillers were constructed with 316SS sheet metal, heavy wall copper coil, 316SS hardware, 316SS control panel, and 3-4 part anti-corrosive paint.
In 2 of the 3 cases, units were specifically designed to match existing footprints but also provide additional capacity over the existing systems that were 25+ years old. FLuid connections were also designed to match existing location. Dimensions were so close to the existing unit(s) and even the electrical ratings were designed around the existing conditions. In some cases, we were actually able to boost the overall system capacity by 20-30% and reduce sound by an average of 3-6 dBA. We built the units with our optional Smart Family XP safeties, which include OSHA condenser handrail system, OSHA ladder with cage, differential PRV’s, purge alarm for Z-purge, and color touchscreen microprocesser.
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