It takes a specially designed gasket material to keep low-temperature fluids in check in cryogenic freezers. A normal seal will freeze solid when such arctic climates are encountered. At that point, jointing brittleness ensues, the issue is likely compounded by ice-saturated creep, and the high-performance substance ends up crumbling. All is not lost, for there are gasket materials that thrive in cryogenic freezers. First, however, what is cryogenics?
According to a reputable engineering resource, cryogenics is the division of science that deals with extremely cold applications. Think of an engineering system that operates below -150°C, and then add liquefied gas to that image. Specialized refrigerants, liquid nitrogen, and a host of other bitterly cold applications, they all fall under this umbrella term. Despite the frosty nature of these equipment usage domains, the ancillary components employed here look just like a middle of the road freezer system. Only, the pipes are carrying liquefied gases, not a partially chilled refrigerant. In light of the rock-bottom thermal state maintained within these pipes and fittings, we need gasket materials that can withstand this chill factor.
Cryogenic Freezers: Selecting Gasket Materials
Advances in polymer engineering have extended the operational temperature range of many advanced plastics families. Despite the kind of temperature extremes that can freeze gases in their tracks, these polymers remain ductile. Furthermore, the selected gasket material won’t contract drastically as the temperature descends perilously low. Polytetrafluoroethylene (PTFE) is often recruited when this usage domain calls for a sealing family that maintains its finest operating characteristics. Branded as Teflon, this synthetic fluoropolymer is known to be a reliable jointing solution, one that’s used in the aerospace industry and those laboratory situations that rely on extremely low temperatures. Tungsten carbide, another capable cryogenics sealing solution, proves there are several options available, including a number of cermets. Fabricated from ceramic and sintered metals, this latter group is defined as a reinforced composite group. Why, though, are these composites making headway as cryogenics gasketing products?
To answer that question, we have to look beyond gasket material ductility and those thermal contraction effects that weaken the seals within a cryogenic system. Curiously, these fluids are classed as poor lubricators. They’re ‘sticky,’ in that the icy boundaries around the gasket cause face adherence issues. Like that time someone’s finger got stuck to the surface of a freezer’s inner housing, the extreme cold creates a dry-stick effect. Fortunately, the selected glass-filled composites and their just as capable Teflon branded gaskets are designed to defeat this phenomenon.
What are water pump gaskets? Are they fundamentally different from other sealing products? Absolutely, especially when those gaskets are employed in situations that imbue water with added energy. For example, a vehicle water pump gasket handles high temperatures and a coolant load, whereas a marine pump seal resists the encroachment of salt. Back to the main query, just what does this gasket type do for a water pump?
Bookends the Inlet and Discharge Ports
In simple terms, water pump gaskets seal the flange segments that hook the pump to the inlet and outlet pipes. If water is drawn by a positive displacement mechanism, such as a volute impeller, it’s the job of this seal pair to ensure the coupling between the pump and those ports is tight. Expect the seal to be manufactured from a fairly rigid elastomer, especially if the gasket in question is bound for an application that uses hot water.
Weighing Fluid Medium Variables
Water is like a blank sheet of paper; we can change it in so many ways. Car water pumps are mixed with coolants while their marine cousins pass a salt-saturated outflow. HVAC water pumps add pressure and greater temperature extremes to the mix. Therefore, the chosen seal material obviously has to match a chosen application. In pressure-sensitive usage fields, the selected material exhibits greater mechanical strength, plus a knack for surviving compressive tightening forces. Other water pump gaskets add chemical corrosion resistance or an intelligently imbued material characteristic that’s designed to resist a specific compound, like salt.
Uniquely Qualified Gasketing Solutions
A uniform pressure pairs with a certain thermal curve to bully a standard pipe seal as it lays between two flange faces. Okay, a change in fluid state or a transient pressure spike pushes that same seal to its design limits, but those limits will normally hold. Water pump gaskets are a little different. They’re positioned around a mechanically dynamic area, a work zone that churns the water and injects it with centrifugal energy. Surrounded by fastener openings and a wide flange face, plus some gasketing sealant, the seal holds firm despite the internal stresses generated inside the pump.
Water pump gaskets, as anyone can guess, are found in every industrial and commercial sector. Even cars have water pumps so that the engine runs cool. HVAC rooms are positively loaded with belt-driven variants, then there are marine pumps driving water through outboard engines so that a svelte boat can skip across a lake surface. It’s absolutely imperative that these gaskets are installed properly, for water leaks can cripple all of these applications.