Canister, break

Although the charcoal canisters are about 95% effective, fuel volatiUty still impacts the mass of vapors that break through the canister. Therefore, EPA mandated that starting in the summer of 1992, RVP levels be reduced below the levels specified in ASTM D4814. Class C regions, generally the northern part of the country, are limited to a maximum RVP of 62 kPa (9.0 psi) vs an ASTM limit of 79 kPa (11 psi), and the southern Class B regions are limited to a maximum RVP of 54 kPa (7.8 psi) vs 69 kPa (9.0 psi) for ASTM. 

In this example, the one liter canister is designed as a cylinder with a length-to-diameter (L/D) ratio of five. The vapor feed stream to the canister is a 50/50 mixture of n-butane and air, and the inlet flow rate is set at 40 grams per hour of n-butane. The curves in the Fig.9 show that break through occurs shortly after the 100 minute point in the load. Up to break-through, the activated carbon bed has adsorbed about 65 grams of HC. 

Hydrocarbon vapor migration within the carbon canister is a significant factoi during the real time diurnal test procedure. The phenomenon occurs after the canister has been partially charged with fuel vapors. Initially the hydrocarbons will reside primarily in the activated carbon that is closest to the fuel vapor source. Over time, the hydrocarbons will diffuse to areas in the carbon bed with lower HC concentration. Premature break through caused by vapor migration for twc different canisters is shown in Fig. 17. The canister with the L/D ratio of 5.0 shows substantially lower bleed emissions than the canister with an L/D ratio of 3.0. 

Another way to examine the effect of carbon particle size on kinetics is to look at the bleed emissions from a carbon canister [20,35]. Bleed emissions are those emissions that occur prior to break through. They are the result of the diffusion of gasoline vapor components that can develop during extended soak times between purge and adsorption events. 

Put on your safety glasses. To make a rocket, fill a film canister about / full of water. Place the canister in the center of the pie pan. Break an Alka-Seltzer tablet into three piece of about equal size. Drop one of the pieces into the canister, snap on its top, and quickly invert the canister so its top is resting on the pie pan. Step back and wait. The pressure inside the canister increases due to the accumulation of carbon dioxide gas inside it. This pressure builds up until the canister body suddenly explodes from the pie pan launching pad. If the top of the canister is quickly replaced and the canister repositioned, another blast can occur. In fact, several blast-offs can be obtained with one Alka-Seltzer tablet. 

Ve have called this the "Conelnalon" of the serlee, because It wraps up the description of a alMpla single-break canister shell. Any further such articles will ocme under the heeding of "Advanced Shell Conatructlon , idiich we plan to cover next year )... 

M40 MASK. The contaminated soldier holds the mask firmly in place to avoid breaking the seal. Make the rolls from each side of the hood come to a point at the bottom of the zipper, forming a V. Put a half twist in the V, forming two sides into a tail. Then tuck the tails between the upper part of the canister and mask. (Tie tail over and under the hose of the M42.)... 

Two copper conical shaped charges (CSC) are used to break open the burster charge canister in the munition and detonate the burster explosives. The CSCs are fired in the direction of the burster at the same time as the ESC is fired. The CSC is a multi-tapered copper device containing 32 grains of Composition A explosive. It was selected because it meets the initiation requirements of TNT and the need for precision and repeatability. 

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