Mick, your rig is nowhere near big enough!
I have a 15CFM twin cylinder compressor with a 200 litre tank, and using a standard machine mart gun of the type you stick in a bucket of grit, it practically ran non stop when I was blasting!
Blasting is Not a fast process either, in fact it's infuriatingly slow at times, and if anything on the surface you're blasting is soft or oily, especially soft paint, it won't get it off, it cushions the grit!
You will also find it creates a fair amount of water in the air feed system, so if you don't have a water trap, you'll need one!
I used my guns in two different situations,
(a), I made my own blast cabinet, modelled on a big floor standing Guyson type with filtered extractor, in which I've blasted everything from small suspension components to Aston Martin & Ferrari V8 and Jaguar V12 cylinder blocks using everything from aluminium oxide, to glass bead and walnut,
(b) the same type gun with a hose stuck in big bags of grit to blast hundreds of square metres of stone wall on an C18 French farmhouse – I wore thick overalls, ear defenders and gloves, plus an air fed helmet ……. and a goodly supply of visor lenses, they frost up in a heartbeat!
One of the biggest annoyances with the hose feed type gun for me, was grit plugging the hose in the hopper, so I'd be forever sticking a thumb over the nozzle to back pressure the plug out!
The gun did a cracking job in each case, but the consumption of air (and nozzles) was astronomical, and in some instances when really going for it, consumption outstripped what my compressor could turn out, and it was New, and as grit rapidly wears the (tungsten) nozzles, they get bigger and use more air!
Whatever you use to blast, Do make sure you protect your lungs, ears and, eyes especially: grit in any form, dry or wet, is bloody merciless on skin tissue wherever it hits, get it wrong and in your face, it's Very nasty, and the dust even from an accidental lungful will have you coughing for days, any sort of grit is nasty stuff no matter how small the components you're blasting!
Whenever you blast media against hard material under pressure, it degrades and creates dust in varying degrees of fineness, and the really fine dust if breathed in, acts in a similar way to diesel particulates, your lungs cannot filter it out and it goes straight into your bloodstream where the body's natural defences attack it with antibodies, so at best, you end up with flu like symptoms and you won't feel good …………trust me, I've been there, fortunately my lungs are still giving 100% oxygen (check up at the quacks last week)!!
If you're going to try blasting some parts, I would strongly recommend you use a cabinet and extractor to contain the dust and, use good ear nd eye protection and at least valve equiped face masks!
I can't say whether wet blasting would work any better because I've never done it, but the grit in the feed will still go every which way when it hits the target, and you'll have some cleaning up to do, unless you contain it!
…………and make sure no stray pressurised grit Ever gets near glass or paintwork on your car or house or anything you value in your workshop, it will at best cover it in fine dust, and at worst if close enough, etch it, and if you carelessly wipe that dust off your car or anything polished, you'll make a wonderfully indellible imprint of that wipe, it's incredibly abrasive, so keep it well away from machinery!
If you're not doing much blasting too often, I'd recommend shopping around engineering shops in your area to see if any of them have a cabinet and offer to cross their palms with silver to have them do it for you!
Basically, it is a ball achingly slow, noisy, filthy, gritty job that will have you standing around for an age getting back ache while you run up a big electricity bill and, probably pee off your neighbours with the racket, compressors hammering away and high pressure air hissing for a long time gets a tad irritating to others, and can cause tinitus if you're close up!
Personally, unless you can do it yourself properly equipped, I'd forget it!
Just my 2p's worth!
John