Compressed Air Couplings

[Clive FosterParticipant @clivefoster55965]

Sorry about topic drift but …

Adrian

Thanks for that useful information about the BS1362-EV sockets. Probably well worth looking for these better ones to run compressors and machine tools. However checking the specifications via MRs Google I was surprised to see that even those are only rated for 10 A continuous.

Mrs Google can’t find a continuous load rating for basic BS1362 sockets, just says 13 A max. Presumably there is some form of minimum time limit or temperature rise too. Given that a BS1362 fuse is specified to pass 20 amps indefinitely and blow at just under 25 amps. It’s a bit worrying to find that the matching socket may well not be able to sustain the same load as the fuse. Which sort of defeats the object of the fuse as a safely device. Although it does perhaps explain why a socket used to supply a heater in a friends house went all black and had to be replaced.

So glad that my workshop 13A outlets are all metal old line industrial distribution boards screwed to the wall. Nominal 30 amp rated switchgear if I recall the specifications correctly.

Clive

[Charles LamontParticipant @charleslamont71117]

I have a couple of the industrial type blue 16A round pin sockets in my shop for the more powerful tools.

[JasonBModerator @jasonb]

What do people do when they want a cup of tea, my compressor is half the wattage of my kettle.

Quick play with a couple of online calculators shows the startup current of the compressor would be 60% of the continuous current from the kettle

As for the contacts in the wall socket being beefy enough, you are assuming that the ones in the cheap compressor switch are going to be more substantial.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, I have the normal 13A socket in my garage for my machines, which have been no trouble, but I do have a 16A and a 32A blue sockets, which I use for my welders and a couple of 110V transformers for my angle grinders, drills etc. which are all used outside, although I do have a smaller 110V transformer with a standard 13A plug on it, and my compressors only have a 13A plug.

Regards Nick.

[JasonBModerator @jasonb]

I had a look at my other Machine Mart Compressor today as it is easier to get at. The same black plastic cover has been broken in exactly the same place as Bill’s for at least 30 years.

Rather than send back for Bill it may be simpler to remove the screw that is holding the small broken piece of cover to the switch body and substitute a longer screw and washer to hold the cover in place. Me I’ll carry on using both by the wall socket switch.

[Stuart Smith 5Participant @stuartsmith5]

Jason

Starting current for a single phase motor could be up to 6 times the full load running current. Only for a very short time though.

Stuart

[Bill PhinnParticipant @billphinn90025]

Thanks for the further replies/discussion.

I’ve been assured that they’ve sourced a replacement part for me and they will be giving me tracking details once it’s despatched. Will update anon.

I’m not qualified to have an opinion on the rights or wrongs of switching power to the machine from “the wall” rather than using the flimsy plastic cover/actuator, but I’ve been using the wall without any evident probs so far and think I’m qualified at least to say the broken plastic part is a woefully flimsy piece of work for doing the job intended for it. Jason’s experience with the one on his other compressor only confirms me in that belief.

Just need to find a 3/8” bore hose now with a decent quick coupling end for the PCL XF/ Euro adapter on my blow gun intake. The Poppstar fitted hose I bought off Amazon last week connects easily enough to the blow gun, but any lateral force exerted on the connection lets air by. I might have to chop off the quick coupling on the hose and fit a branded PCL one.

While we’re on hoses, does anyone here use an anti-whip hose along with the main hose, and when or why is one advisable?

[noel shelleyParticipant @noelshelley55608]

Stuarts comment on inrush or starting current is on the conservative side, the figure CAN be 1200% of full load current on single phase motors. This occurs for only milliseconds followed by the run up to start winding cut out. The run winding current is listed on the data plate, this is the figure that your overload/contactor should be set at. The overload is a device that can stand the overload for a short while eg on start up, but if this continues then it will cut out, (hopefully ) saving the motor. A run current of typically 2-3amps will be fed by a 13A fuse to stand the start current but will offer all but NO protection to the motor. On a single phase motor with a centrifugal switch and cap, if the operator is not in the know the motor will burn out, if one or both fail without an overload.

How many of us have lost a good and expensive motor because we have use a 13Afuse and plug instead of an overload device ?

If a new motor fails and is not wired through an overload device your guarantee will be void.

Noel.

[Robert Atkinson 2Participant @robertatkinson2]

I’ve got to agree with Clive, the inrush current is much higher thn the starting current. Contacts designed for high inrush loads like motors and incandescent lamps use specific alloys in theiere contacts. Cadmum was ony component but that is now banned. The high inrush contacts tend not to be suitable for low current switching (won’t breakdownthe surface oxides) so there is no simple solution. Areospace relay tend to use a higcurrent base alloy with a gold overplate. Thia allows use in both power and signal circuits. However once used for power they can’t be used for signals as the gold overplate is removed.

A 13A twin outlet is only rated for 13A total shared between both sockets.

Robert.

[noel shelley]

On noel shelley Said:

 

If a new motor fails and is not wired through an overload device your guarantee will be void.

Noel.

I suppose the maker could also argue that chopping off the supplied moulded on 13A plug to fit something else could invalidate and warantee.

[noel shelleyParticipant @noelshelley55608]

Hi Jason, The context here was a new motor, these are not normally supplied with any wiring or plug. I was recently asked to put a new 3Hp motor from Clarke I believe on a compressor and read the installation notes with interest – repeated here. The compressor had been supplied as new some years before with a 13A plug. One could have wired a 13 Socket to the overload device to avoid removing the plug ?  Noel.

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