O-ring cap seal

As I said, microscale equipment design is in a state of flux, but there are a few things to note about the O-ring cap seal ... 

If your capillary gas delivery tube was connected directly to a conical vial with an O-ring cap seal (Fig. 39a), you have to undo the seal on a hot vial ( )... 

With the gas collection reservoir, you have an O-ring cap seal with a Teflon-faced plastic insert. Pierce the insert with a hypodermic syringe and draw off some of the product. Usually, you put this gas through GC (see Chapter 30, Gas Chromatography, for particulars). 

Oh. Check out the O-ring cap seal discussion for a perspective on microscale vacuum distillation (see Chapter 6, Microscale Jointware ). 

Both columns have endflttings that attach directly to the column tube, i.e., the tube itself is threaded. The column on the left is manufactured from stainless steel and the column on the right from PEEK. Note that the frit for the stainless steel column is actually press-fit into a cap that fits on top of the column, whereas the frit for the PEEK column fits inside a deformable O ring that seals when the column end-fitting is tightened to the column tube. 

Auto uses are said to account for about one-third of the 30000 tonnes of silicone rubber consumed annually around the world (in turn about 10% of total silicone consumption). Specific uses include shaft sealing rings, spark plug caps, O-rings (the major market for the fluorosilicones), gaskets, coolant and heater hoses for buses and trucks, and ignition cables. 

Valves of all sizes which are only used occasionally will he sealed with O rings. As a safeguard against leakage, they have no handwheel fitted and the stem is provided with a covering cap which is only removed when the valve is to he operated. The stem will have flats for operation hy a spanner. Most such valves can he hack-seated to permit changing the O rings. 

Prior to installation of the end caps, the head seal should be installed. The head seal is an O-ring to prevent feed/concentrate from leaking out of the end caps. Figure 4.22 shows the location of this O-ring, as do Figures 6.12 and 6.13. 

So, since nobody actually has any microscale reduced-pressure distillations, and with certain sizes of equipment the O-rings can squeeze out from under the plastic caps, and since I don t use them for reduced-pressure (vacuum) distillation anyway (I switch to a semi-micro apparatus with real 14/20 joints and—gasp —grease), I don t know how vacuum tight these seals really are. 

You would think that with an O-ring and a Teflon-faced plastic disk wedged under the cap, this would make a very tight seal. Think again. One of my... 

Figure 5 illustrates an upflow soil column (18 x I-in. inner diameter) with screw cap fittings and watertight O-ring seals. Soil 250 g) is supported by... 

A sliding O-ring seal was provided at the center of the upper cap for positioning of the 3/8-inch o.d. by 0.032-inch i.d. quench probe along the central axis of the reaction tube. Cooling water was supplied to the quench probe at a metered rate of 1/3 g.p.m. The entrance tip of the probe was typically located at the center of the uppermost winding of the load coil. 

Fig. 1.8 A wedge-type piston seal (A) antiextrusion ring (bronze), (C) retaining precompression cap, and (I) O-ring. (From reference 1.)...

H. Thermoregulator. I. Thermometer. 1. Screw cap. 2. Teflon plug. 3. O-ring seal (bleed hole to remove air). 4. O-ring seal. 

The rubber o-ring that was used to seal the Teflon cap became brittle. 

Stainless steel cap with screw thread and O-ring seal (teflon coated)... 

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