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Friday, 2 November 2012

RO Machine - Part 5

Back to the test gear mainly for today. A couple of bottles of calibration solution arrived in the post after my dubious home brew solution results.

1-HM Digital 342ppm Calibration Solution.22

First of all i felt it would be wise to acclimatise all the equipment and solutions to the same temperature. Not an easy feat in the home domain!

Thankfully the airing cupboard with the central heating thermostat locked inside at a temperature of 25deg, worked out quite nicely!

2-RO Machine.45

I gave everything a good 4 hours to settle to temperature.

First up the TDS-4TM…

4-HM Digital TDS-4TM.40

Passed pretty much on the money!

Next the PS-202…

7-HM Digital PS-202 TDS Controller.29

Came in a little shy of 342ppm, and seeing as the calibration solution is static and not flowing, as per the instructions 3% should be added to compensate, so i was aiming for 352ppm…

A quick tweak of the adjustment pot and it was good to go…

8-HM Digital PS-202 TDS Controller.32

The numbers do fluctuate a small amount and the adjustment is quite sensitive, but I'm happy this is close enough.

Next, the TDSmeter2 DM-2 that i have been relying on for sometime and showed very odd results on my home made solution…

5-HM Digital TDSMeter2.14

6-HM Digital TDSMeter2.28

Both sensors were over a hundred out…

This verified yesterdays results but has me baffled as to why it is so high? When running the RO Unit its never shown anything so errant and has been capable of showing the water at 0ppm which is indeed backed up by the two other measuring instruments.

I had noticed the digits on the screen were getting a little dim, so thought the battery power may be lacking and affecting the results.

I switched them out and their was no change at all.

So i adjusted each channel to the (3% above) 342ppm calibration solution…

9-HM Digital TDSMeter2.56

Then tested the probes in both some RO and straight from the tap water and it showed spot on results of 0 and ~270ppm respectively… very odd!

Although I'm now happy all my devices are on a level playing field with what they are telling me!

I have set a schedule in my 2Do App to check these again on a 6 month interval for the future.

On another note, a bit more on electronics, got a little more done with the button/switch interface board, just needed some header pins, so i nipped out to Maplin’s to pick some up after doing an online stock check, only to get there and they couldn’t find them… bugger! Will just have to order some online.

3-RO Machine.49

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