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Default How to tell if a UV lamp is working?

Andrew Gabriel wrote:
In article ,
writes:

How can one safely tell if a UV lamp is working? This is a UV tube in
a pond filter system which lives in a lightproof (well, UV proof I
suppose) tube with the water going to the filter flowing past it.

It has standard fluorescent gear, a choke and a starter.


Often they have a little fluorescing plastic indicator in the
case, to show it is picking up UV. You should change the tube
annually anyway (assuming 24x7 operation), as UV output drops,
and in continuous operation the output will become too low before
the tube fails in the conventional ways (i.e. not starting).
If you are doing this and the unit is drawing roughly the right
current, I would assume it's working unless you have some other
reason to suspect it (e.g. pond going unexpectedly mankey).
When operating, it may generate some ozone which you might be
able to smell from the casing, but they don't all do this.

I hope the unit has interlocks to prevent you looking at the
tube operating, which is dangerous. However, if you are tempted
to try defeating the interlocks, put a sheet of glass (not
plastic) between you and the lamp, stand well back, and only
operate the lamp for a few seconds. There is normally a dim
visible glow from the clear tubes.


Thanks, we have two spare tubes (it's ex. my mother-in-law) and I
doubt very much if the tube has been replaced within living memory so
I'll change it anyway.

--
Chris Green