Rust, Humidity and Temperature Measurements

Over the last two and a half years the trust has been carefully monitoring and measuring the temperature and humidity at Sandfields Pumping Station. The aim of this study is to gain a fuller understanding of how best to preserve the bright works on the Cornish engine and to understand the factor that cause rust along with the idea conditions and treatment to prevent it.

Here is the latest report form the engineering team:

The one working humidity/temperature data logger was left ticking over in the ground floor of the engine house from mid-March until a couple of weeks ago when I returned to active service. I’ve attached a screenshot of the data- at least it makes a change from graphs of Covid-19 infection rates. It’s interesting(ish) because it shows the pattern of variation over an extended period (nearly 6 months), whereas previously I’d been looking at chunks of time of only 2 or 3 weeks.

As can be seen, for much of the time the %RH was in the range 60-70%, with values above and below this range mainly coinciding with spells of particularly warm or cold weather. Keen observers will also notice that there was another incidence around the end of March when a temperature spike of 60+ degrees was recorded- the spirit’s still about.

60-70%RH is in the range where some atmospheric corrosion of iron/steel would be expected. However most of the engine remains relatively unaffected, helped I’m sure by the Steelguard we’ve applied.

I’ve also included “then and now” photos of three areas I taped off in October 2018 (is it really two years ago?) and left untreated. In two cases there’s very little difference, whereas where the pump rod attaches to the beam there’s noticeable corrosion. I think this is more likely to be down to differences in material (eg chemical composition) rather than in location. I’ll leave the data logger to record for the next 6 months to get a comparable picture over winter.

About morturn

Historian – Photographer – Filmmaker Retired construction professional with a passion for public, social and industrial history. I believe in equality, dignity and integrity for all. Don’t like people who try to belittle the ambitions of others. I am of the opinion that my now life belongs to the whole community and as long as I live, it is my privilege to do for it whatever I can. I want to be thoroughly used up when I die, for the harder I work the more I live.
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1 Response to Rust, Humidity and Temperature Measurements

  1. David Dundas says:

    Great work by our volunteers and preventing the rusting of cleaned steel parts is a challenge. It is interesting to note that the top bell shaped valve cam in the picture on the left is seriously worn on the right side and will be need to be replaced before the engine is put back to work

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