Left-handed thread fittings

Use compatible pipe fittings. (Flammable gas cylinders have valves with left-hand threads cylinders for oxygen and nonflammable gases, except occasionally helium, have valves with right-hand threads. Certain liquefied gas cylinders have two supply lines, one for gas and one for liquid, dependent on cylinder position.)... 

To prevent interchange of fittings between cylinders of combustible and non-combustible gases, the valve outlets are screwed left-hand thread and right-hand, respectively (Table... 

The CPA or "Snake Pen" consists of a pen body containing a porous wick, such as that used in felt pens, and a solution ofDMSO and any number of toxins. When the wick is touched to the victim s skin he receives a fatal dose of poison. The CPA is built from a correction fluid pen, available at any office supply store. These pens have a soft, flexible body and are easy to modify. Unscrew the top from the son pen body, squeeze out the correction fluid and flush the interior with solvent to remove all traces of its original contents. Note that most of these pens have a left-hand thread on the body. The tip of the pen is sawed off and the valve stem carefully removed. Ream out the pen tip to fit the wick. A felt tip marker pen works well as a wick, after being soaked and rinsed in sol vent to remove traces of ink. It may be necessary to trim the wick to fit. Press the wick into the pen tip until about 3/8 " protrudes and seal around it with silicone sealer. When the sealant is dry, put on rubber gloves and, using a hypodermic syringes, inject the DMSO solution into the pen barrel until it is about 3/ 4 full. Be sure not to squeeze the pen while accomplishing this. Coat the barrel threads with a little silicone sealer, screw on the cap and allow the pen to dry in a vertical position. Line the inside of the cap... 

Fig. 10.1. Some common high-pressure tank fittings. The seal in the top three fittings is made by contact between the nipple in the connection and the seat in the outlet. Note the cone-shaped, round, and bullet-shaped nipples for (a), (b), and (c) respectively. The bottom connection (d) is sealed by means of a flat soft-metal gasket. Never attempt to mix outlet and connections between the various designs. Note the grooves on the connection nuts for connections (b), (c), and (d). This groove indicates a fitting with left-handed threads. (Reproduced by permission of the copyright holder, Mathe-son Gas Products, Inc.)...

Screw the fitting onto the cylinder and tighten firmly. A poor fit probably means that the regulator is not of the correct type. (Note that some cylinders have left hand threads.)... 

A left-handed baseball player (chiral) can use the same ball or bat (achiral) as can a right-handed player. But, of course, a left-handed player (chiral) can use only a left-handed baseball glove (chiral). A bolt with a right-handed thread (chiral) can use the same washer (achiral) as a bolt with a left-handed thread, but it can only fit into a nut (chiral) with a right-handed thread. To generalize, the chirality of an object is most significant when the object interacts with another chiral object. 

To prevent interchange of fittings between cylinders of combustible and non-combustible gases, the valve outlets are screwed left-hand and right-hand thread, respectively (Table 9.2). Primary identification is by means of labelling with the name and chemical formula on the shoulder of the cylinder. Secondary identification is by use of ground colours on the cylinder body. Unless specified in Table 9.2, gas and gas mixtures shall be identified by a colour classification indicating gas properties in accordance with the risk diamond on the cylinder label e.g. 

Left-handed nuts and fittings have a notch cut into the comers to help identify the direction of the thread. 

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