RACA Journal June 2016 - Page 77

Tool Talk Continued from page 73 Size matters Although charging hoses are available in various lengths i.e. 90cm, 120cm 150cm, 180cm and 240cm and longer, the best results are achieved with the shortest possible hoses. Pressure ratings – minimum burst and maximum working pressure Standard charging hoses are rated between 500 and 750psi (34-51 bar) working pressure with a 2 500-3 000psi (172-206 bar) burst pressure and are not compatible with the higher pressure refrigerants such as R410a. When working with R410a only a premium quality hose with a rating of 4 000psi (276 bar) minimum burst and 800psi (55 bar) maximum working pressure should be used. Pressure ratings, certification and quality markings (SAE, UL) can be found printed along the length of the hose. 1 2 • • • • will be specified in the manufacturer’s specification. Replace the hose if it has been kinked or bent beyond its bending radius; it will no longer be safe to use as the structural integrity will have been compromised. Gaskets should be inspected and replaced regularly. Every so often, give the hoses a good wipe with a damp cloth and a mild non-abrasive detergent (diluted dishwashing liquid) to get rid of oil and dust and keep them looking good. Avoid storing them in direct sunlight. It is recommended that hoses are replaced at least every five years. Couplers and adaptors While having the shortest length of hose with the most appropriate service end is recommended, realistically there are situations when this is not possible and an adaption to deviate from the norm is required. There are several fittings and couplers available to overcome just about any situation and a few standard ones should be included in every technician’s tool kit. A good selection to start with would include a hose coupler to couple two hoses in order to extend the length of a hose, a set or two of conversion couplers i.e. to convert from 1/4” to 5/16” and vice versa, a couple of ball valves in different sizes. Other useful fittings such as a vacuum pump intake adaptor, a liquid charging adaptor, refrigerant cylinder adaptor and a couple of braze in fittings can be added over time. Couples and adaptors. 1 & 2: Ball valves are available either as an integral part of the hoses, or separately. When working with higher pressure refrigerants such as R410a ideally, the hoses should have ball valves at the service end to isolate the hoses from the system. Ball valves are available either as an integral part of the hoses, or separately, as well as in various sizes such as 1/4” M x 5/16” FFL for R410a systems. Caring for your hoses • Do not bend or kink your hoses. Hoses have a limited bending radius (ca. 152mm depending on manufacturer); generally this www.hvacronline.co.za Charging Tools and accessories Pressure and temperature chart With fewer refrigerants available in the past, seasoned technicians would use a slide-rule pressure and temperature chart – usually supplied free of charge – to determine the required temperature and pressure of a system. Over time, they could even recall those by memory. With the number of different refrigerants that are in use at present this is no longer practical. Smartphone users can download p/t apps from the app store or google and most digital manifolds are preloaded with the variety of commonly used refrigerants’. Continued on page 77 RACA Journal I June 2016 75