the wing p4.7 combat rubber raiding craft crrc , also known as the 'combat rubber reconnaissance craft,' is a fabricated from cooley coolthane polyurethane fabric and is currently in operation with the u.s. navy, u.s. marine corps, the u.s. army, nasa and others.
anti-fog agents, also known as anti-fogging agents and treatments, are chemicals that prevent the condensation of water in the form of small droplets on a surface which resemble fog.anti-fog treatments were first developed by nasa during project gemini, and are now often used on transparent glass or plastic surfaces used in optical applications, such as the lenses and mirrors found in glasses .
a backflow prevention device is used to protect potable water supplies from contamination or pollution due to backflow.. in water distribution systems, water is normally maintained at a significant pressure to enable water to flow from the tap, shower, or other fixture.water pressure may fail or be reduced when a water main bursts, pipes freeze, or there is unexpectedly high demand on the .
a tremie is a watertight pipe, usually of about 250mm inside diameter 150 to 300 mm , with a conical hopper at its upper end above the water level. it may have a loose plug or a valve at the bottom end. a tremie is used to pour concrete underwater in a way that avoids washout of cement from the mix due to turbulent water contact with the concrete while it is flowing.
two men operating a rotary diver's air pump rotary pumps are driven by a crankshaft that is rotated by handles on two flywheels attached to the ends of the shaft on each side of the pump. rotary pumps were built with one, two or three cylinders , 3 and are operated by a team of two men.
water pump seal lubricant is also added. antifreeze was developed to overcome the shortcomings of water as a heat transfer fluid. on the other hand, if the engine coolant gets too hot, it might boil while inside the engine, causing voids pockets of steam , leading to localized hot spots and the catastrophic failure of the engine.
hazard substitution is a hazard control strategy in which a material or process is replaced with another that is less hazardous. substitution is the second most effective of the five members of the hierarchy of hazard controls in protecting workers, after elimination. substitution and elimination are most effective early in the design process, when they may be inexpensive and simple to .
such standardized measurements can produce two quantities: abrasion rate and normalized abrasion rate also called abrasion resistance index . the former is the amount of mass lost per 1000 cycles of abrasion. the latter is the ratio of former with the known abrasion rate for some specific reference material.
a cramp is a sudden, involuntary muscle contraction or overshortening; while generally temporary and non-damaging, they can cause significant pain and a paralysis-like immobility of the affected muscle.onset is usually sudden and it resolves on its own over a period of several seconds, minutes, or hours. cramps may occur in a skeletal muscle or smooth muscle.
natural rubber is an elastomer and a thermoplastic. once the rubber is vulcanized, it is a thermoset. most rubber in everyday use is vulcanized to a point where it shares properties of both; i.e., if it is heated and cooled, it is degraded but not destroyed. the final properties of a rubber item depend not just on the polymer, but also on .
hydro blasting is not a form of abrasive blasting as no abrasive media is used. hydro-blasting, commonly known as water blasting, is commonly used because it usually requires only one operator. in hydro-blasting, a highly pressured stream of water is used to remove old paint, chemicals, or buildup without damaging the original surface.