HM Digital In-line TDS meter with 15mm John Guest

PROBLEM SOLVED SCROLL DOWN FOR NEW PROBLEM

My whole system is plumbed in using 15mm push fit tubing and fittings.

For some annoying reason Gardiner only supply imperial fittings for their inline TDS meters so I thought okay I’ll get the 1/2” t-pieces and the 1/4” probes, a metre of 1/2” tubing and 2 x 1/2” push fit to 1/2” BSP male thread.

I already had some 15mm push fit to 1/2” brass BSP female thread.

To make it work I was basically going to do this:

15mm tube > push fit brass-1/2” female BSP > 1/2” male plastic BSP-1/2” push fit > 1/2” tube > 1/2” t-piece for TDS probe > then everything else in reverse out the other way.

Ordered it and received it today only to find the 1/2” BSP push fit piece doesn’t work with the 15mm push fit to 1/2” thread?

I tried several different fittings but neither of them screwed?

What other type of thread/fitting is there to make this work?

I’d rather not have to change all my fittings and tubing just to fit this one 1/2” fitting.

Has anyone used an inline TDS meter before with 15mm tubing?

Thanks.

ABOVE PROBLEM SOLVED....

However...

The model I have is HM Digital TRM-1 which is the 3 probe version.

My RO is in the van by the side door and fills the tank at the inlet there. Then at the back doors the pump draws from the outlet and through my DI and then to my hose reel.

The cables that go from the unit to each probe are just shy of 60cm!!

Even if the unit is mounted at the back it barely reaches the nearest pipe let alone the RO by the side door.

Can I splice the wires and lengthen them using some spare wiring I have lying around? Or is it some sort of special wiring?

HM digital must have assumed that all three lines would be in such close proximity to each other...grrrrrr

Have you got any 1/2 inch tails with barbs? Just get some normal 1/2 inch hose pipe and push it over your 15mm if pipe with insert and jubilee clip it, then the hosepipe over the barb into TDs meter. 

Ifyou don't have barbs just jubilee clip it over 1/2 inch hose. Should hold okay.

http://gardinerpolesystems.co.uk/all-products/pump-hose/hose-fittings-adapters/john-guest-fittings/1-2-fittings/a-john-guest-stem-to-a-barb.html

Dr Von Samstein said:

Have you got any 1/2 inch tails with barbs? Just get some normal 1/2 inch hose pipe and push it over your 15mm if pipe with insert and jubilee clip it, then the hosepipe over the barb into TDs meter. 
 
Ifyou don't have barbs just jubilee clip it over 1/2 inch hose. Should hold okay.
 
http://gardinerpolesystems.co.uk/all-products/pump-hose/hose-fittings-adapters/john-guest-fittings/1-2-fittings/a-john-guest-stem-to-a-barb.html

Click to expand...

Don’t worry I sorted the issue with the thread. Went to B&Q on the way home and picked up some plastic ones and they work a treat.

Got a new problem though which I’ll edit on the first post [emoji23]


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I believe that it's just two core standard wire so splice, crimp and extend.

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Jordiebarrett said:

I believe that it's just two core standard wire so splice, crimp and extend.

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Click to expand...

Don’t mean to doubt you but it’s a £40 unit so don’t want to knacker it, are you definitely sure before I cut up the wire? [emoji23][emoji51]


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Brandon, I doubt myself [emoji23] Far as I'm aware there should be no I'll affect. On my meter the wire has got writing on it which states the gauge so I can't see why extending it with the same size should make any difference unless you go silly with the wire length. Maybe@spruce can help too?

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Jordiebarrett said:

Brandon, I doubt myself [emoji23] Far as I'm aware there should be no I'll affect. On my meter the wire has got writing on it which states the gauge so I can't see why extending it with the same size should make any difference unless you go silly with the wire length. Maybe[mention=125]spruce[/mention] can help too?

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Click to expand...

Yeah I get what you’re saying. I guess all the probes do is send a signal down the wire and the chip in the meter receives it and gives a reading.
Would this do the trick?



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Brandon said:

Yeah I get what you’re saying. I guess all the probes do is send a signal down the wire and the chip in the meter receives it and gives a reading.
Would this do the trick?

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Click to expand...

Don't see why not. Maybe go down a gauge as that looks very thick, at least compared to my meter. Also shielded cable wouldn't be a bad shout. Looking on Google the meter works by testing the resistance of current put down the wires at the tips.

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Jordiebarrett said:

Brandon, I doubt myself

Far as I'm aware there should be no I'll affect. On my meter the wire has got writing on it which states the gauge so I can't see why extending it with the same size should make any difference unless you go silly with the wire length. Maybe@spruce can help too?

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Click to expand...

I'm afraid I don't know the answer to that one.

The probes measure the conductivity of the water. The more minerals and dissolved solids in the water the greater the conductivity. The TDS meter will translate this into a figure that we have come to understand. No dissolved solids in the water means a blank reading or zero.

What one needs to be aware of is that as you join and add wire into an existing loom, you are going to increase the resistance in the cable, especially at the joins. (We are all aware that the long the cable the higher the voltage drop.) So I would hazard at a guess and say that this will also mess with the tds readings.

However, that said, what would happen if you spliced in the same length of cable to each probe and then rechecked the calibration settings afterward? You might then have to adjust the setting with a know water quality using calibration fluid. (Daqua used to sell it.)

I'm not recommending you do this, maybe @doug atkinsoncould enlighten us further as I wouldn't like to take responsibilty for suggesting something that sounds good in theory but that doesn't work in practice.

I have one of these inline tds meters on my r/o system. It has 2 probes, in and out. I have the first probe in the pipework just before my di vessel and the second after my di vessel. Both probes have penty of cable. If I had a third probe I would fit it after the prefilters and before the r/o. Again that probe would be within a few inches of the others, so cable length would not be an issue.

In the OP's case, I would try to rearrange my r/o system to accommodate the probes without having to modify the leads. 

.

This third feed you're trying to measure, could you not run a feed back towards the meter and then run it back down again. Then put the probe in near the meter? For a couple of extra meters of pipe as a flow and return would save cutting wires?

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I’d would also try rearrange your set up. Using extra hose like jordiebarret suggests seems a good idea. I would be concerned that the TDS meter uses accurate measurements of electrical current to measure the water impurity and the extra cable length may affect its reading accuracy. I’m not an expert with electrics though so I may be completely wrong


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You all make some very good points lads. I'd rather not mess with the wiring so looks like I'll have to run the RO inlet pipe to the back of the van for the probe and then return it back again to the side door. It seems silly that HM Digital made the wires so short?

Thanks for your help guys  :1f44d: