Plumbing Joints: Capillary Connectors
Before making a capillary joint, careful preparation is necessary. You must first ensure that you do not set the surrounding area alight. A butane-torch is easier to use than a petrol or paraffin torch. Set the torch, after igniting, to a hard, medium blue flame. Butane produces a very hot flame, so take care to keep your hands well clear.
The soldered fitting contains a reservoir of solder in a ring within the fitting. The end-feed pattern does not contain solder and this has to be introduced into the mouth of the fitting during connection. Some unsoldered fittings are pre-tinned to facilitate the jointing process.
Check that ends are cleanly cut and free from burrs. It is then necessary to clean both the tube ends and the inside of the fitting; this can be done using fine wire wool.
Next, apply a smear of flux to the mating surfaces. This helps to prevent an oxidizing process from occurring which may nullify the solder bond.
A special ‘aggressive’ flux is necessary for jointing stainless-steel tube. This removes the oxide film, which forms more quickly on stainless steel than on other metals. Several types of such fluxes are available, in both liquid and paste form, most containing an acid base. All excess flux must be wiped clean from the surface after jointing.
Techniques for jointing both copper and stainless steel are similar. Insert the pipe into the fitting up to the stop end. You can join a section of pipe at one end only, by standing the unjoined end of the fitting in a lid of water to prevent solder from melting. However, it is best to complete all joints and solder all connections as one operation.
Wipe off any excess flux and apply heat evenly to the mouth of the fitting. Do not concentrate heat at any one point and avoid applying heat after the union is complete, or the solder will blacken and break down. Choose a cored solder as this is easier to use.
The joint is complete when a ring of solder appears completely around the mouth of the fitting. An added precaution is to touch a piece of cored solder around the mouth, while the fitting is still hot, to consolidate it.
End-feed fittings are heated evenly with the blow torch and the solder wire is applied to the mouth of the fitting and slowly rotated until the mouth will accept no more. Leave a ring of solder around the edge.
Do not disturb newly made joints; allow them a minute or so to cool.
Plumbing Connections: Fittings
There are three main types of fitting:
• The straight coupling
• The bent coupling, or elbow
• The branch fitting.
Straight threaded couplings used to join iron pipewoirk are known as nipples or unions.
The bent coupling may be right-angled or obtuse, swept or ‘slow’. Similarly, a branch fitting may be right-angled or obtuse. The most common branch fitting is the tee-piece, so described because of its resemblance to the letter ‘t’. This is used where a connection or branch has to be made in a section of pipework.
Where a smaller-bore pipe has to be connected to a larger outlet, reducing sets can be used. Both capillary and compression adaptors are available to reduce the diameter of the pipe bore.
Another situation which may be encountered is the matching of tubes of metric and imperial gauge. In some sizes, these measurements do not exactly correspond. Sets are available to match metric and imperial pipework and fittings. There are special devices made to reduce or expand tube to metric or imperial dimensions.
Where a pipe or branch has to be terminated either permanently or temporarily, stop ends can be used in conjunction with fittings. These are available for use with both compression and capillary fittings. Where the termination is only temporary, a compression stop-end fitting may be used, as this is easily removed.
The terminations of fittings are described in a specific order. For example, a tee-piece fitting, which is one with more than two outlets, with two equal 15mm outlets and a 22mm branch is described as a 15mm x 15mm x 22mm tee. In other words, each end dimension is given first, followed by the size of any branch.
Fitting outlets are equal or unequal. An equal tee, for example, is one where all outlets are of the same diameter.
Some threaded fittings are known as male-iron or female-iron fittings and traditionally connect to threaded iron connections. The other ends of the fitting may terminate with either compression or capillary ends.
These fittings are usually used on boilers, hot-water cylinders or storage appliances, such as cisterns, and have to be sealed with either PTFE tape or hemp and non-toxic jointing compound. The hemp is ‘teased’ into a thin string, smeared lightly with a plumbing compound and wrapped round the joint.
PTFE tape is a white plastic which is wound round the threads of the fitting in an anti-clockwise direction for about one and a half turns. The fitting is tightened in the normal way, with a spanner.
Pipes should be clipped to walls at intervals. Various types of pipe clip are made. With some the clip is fitted in place first; in others, clips are fitted over the pipe, which is positioned first. Where pipe is taken through walls, sleeving (one pipe size larger than the pipe) should be used, so that pipes are not pinched and to allow for expansion of hot water.
10. November 2011 by admin
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