I think that, for a decent reply, you may need to be more specific in your questioning.

Probably wrongly but I think that the legionella is held in the water, not in the valve of a water system. This being the case, anything you do to check for/eradicate the possibility of legionella would take care of the valve.

Benzene - in what context would it be in a valve - purposely (in the system by design) or accidentally (after an 'incident' of some kind where it should not be)?

I am prepared to be immediately corrected on both counts if I am incorrect (and I may learn something further today!).

Good luck with whatever it is for which you are looking.

Dont have too much knowledge on the issue of Benzene in valves so cannot assist there!

On the other issue, Nidan is correct up to a point.

Legionella Bacteria is common in nature and can be found in low numbers in soil, surface waters, rivers and ponds.

Like all organisms, Legionella has favourable conditions

- bacteria survive but to not multiply below 20°C
- 20-46°C is ideal for growth and reproduction (30-40°C is favoured range)
- Above 46°C some bacteria is killed (above 50°C 90% killed within 2hrs, at 70°C death is instantaneous)

Bacteria needs a supply of nutrients to multilpy, hence algae, amoebae and other bacteria provide a good source of nutrients.

Grows better if undisturbes and scale, sediment and biofilm can protect legionella from the effects of temperature or any biocidal controls
Stagnant areas also allow time for growth.

The only way legionella would possibly be present in valves is if they are inoperable for a period of time! (how long is anyones guess, and would obviously depend on the favourable conditions needed to encourage growth).

If the valve is used regularly, then it is very unlikely to demonstrate the presence of any legionella bacteria, a this would be flushed away before it had the chance to grow!

Three key principles can reduce the proliferation of legionella -

Cleanliness
- keep systems clean & well maintained
- use a suitable water treatment programme
- avoid using materials in system which can harbour or provide nutrients for bacteria
- prevent access by rodents/insects/birds (bird/vermin screens)
- use approved fittings/materials (wras approved)
- flushing regime

Stagnation
- avoid stagnation/deadlegs
- avoid linked tanks
- regular testing of fire hose reels (consider removal if not required)

Temperature
- avoid water temperatures between 20-55°C

ACOP L8 is a useful source of reference as well

Have no doubt others will add comments, but at least this will give you a basic understanding

Benzene, unlike legionella, is unlikely to propagate (!) and presumably comes from the pipework or vessel that the valve is connected to. In this case, the procedure for dealing with or controlling the benzene should be based on what you currently do with the bulk material. More info would be helpful.