Home Forum Chat Forum Moisture meters

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• Moisture meters
• I *think* it’s by mass, as they use electrical conductivity (to wildly varying degrees of accuracy) and IIRC, this comes back to mass.

I am not a wood flooring expert. 🙂

Stoner
Subscriber

I never trust a sawdust manufacturer. So will wait for corroboration 🙂

Stoner
Subscriber

Like for firewood, paper, floor substrate etc.

Do they report a reading of moisture as a percentage of volume or mass?

Am trying to work out the change in mass of a sample of wood as a result of a change in moisture content reading – since I have figures for density of water and dry wood matter I just need to know whether the ratio is by mass or volume. I think ❓

zokes
Member

just weight some, stick it in the oven at about 80 for 24 hours or so, then weigh it again. Moisture content is the mass you lost.

(Unless you set your oven on fire. We do have special ovens for this, and soils aren’t that flammable. YMMV)

What species of timber is it?
How old?
Which part of the tree?

(All variable 😛 )

Most importantly, what make is your MulletusMaximus and how much did you pay for it?

sharkbait
Member

You doing a test on some logs Stoner?
I’m testing a piece of pine that I split on April 23rd (12 x 7.5 x 24cm = 2160cm3) when it weighed 1.87kg. Today it weighs 950g which is a loss of 49%….. but how do you calculate what the current moisture content is?

sharkbait
Member

Actually, a bit of google foo (cheers arbtalk) has unvealed the following:
Average weight of seasoned timber 15%moisture content
pine=m3=600kg
larch=m3=500kg
dougfir=m3=500kg
spruce=m3=400kg
hardwoods
Beech=m3=720kg
Ash=m3=700kg
0ak=m3=740kg

so 1000000/2160=0.002160 x 600 = my log should weigh about 1.29kg when ‘dry’. Another [furniture] site gives pine to be 400kg/m3 which would mean my log should weigh about 860g when dry but that could be very very dry.

Given that the rate of drying has slowed over the last 4 weeks I reckon another 8-12 weeks should see it cooked!

Stoner
Subscriber

What species of timber is it?
How old?
Which part of the tree?

(All variable )

And all irrelevant for energy calcs as all wood (lignin) has basically the same energy and mass density regardless of species or age etc, as long as you are doing your are taking into account moisture content you can calculate the total net energy within a sample with basic maths. (more or less)

zokes – I might tray that one day. What Im trying to do is make an estimate of the total mass of moisture free wood matter in a pile based on some samples and adjusting for moisture content (by mass it would seem) to project total net energy output at a forecast moisture level of c.15-20% when the wood is seasoned.

I use a moisture meter sharkbait. A tenner of eBay.

sharkbait
Member

I use a moisture meter sharkbait. A tenner of eBay.

Me too but I thought it would be an interesting experiment and I could see if the MM was telling the truth!

Stoner
Subscriber

SB – Im going to use similar maths but by using % moisture by mass I can project how much net energy (function of mass of lignin + water, moisture % by mass, and volume) I will get out of a pile of logs at any given moisture reading.

Ah roight, so per mass unit, does wood give out the same energy regardless of species? So, say a piece of oak will be heavier than a piece of pine, but will contain roughly the same amount of lignin per mass unit? And therefore will give out more heat? Is that what you mean?

My phone autocorrected MM to MulletusMaximus as I tweet him and it’s a shortcut. 😕

Stoner
Subscriber

I thought you were passing nastursiams about my hair cut again!

The MM is a chinese thingy. Im fairly happy that it’s accurate enough for my purposes and doubt its any much worse than a branded one.

For a given moisture content the amount of energy per Kg released from any two species of tree will be more or less the same.

So, now that I know that the MM reads moisture as a proportion of mass I can do my calcs…

Had a BIG day at the coppice last weekend. Will post a thread in a few days when Ive sorted it all out. But all I will say is mcmoonter better be sitting down for this one 😉

The meters we use (for concrete and wood) cost upwards of three hundred squid. 😯 But they’re Tramex and unless you’re using one on a site, everyone gets a bit sniffy. I’m sure that’s how they survive.

Tbh, I often wonder if a chinese jobbie from eBay would be accurate enough to do for say a year, chuck it and buy another one.

Stoner
Subscriber

for a tenner why not get one and run them side by side for a while?
Maybe with a slip of paper in the case to make a note of the two readings? See if accuracy is a) acceptable b) consistent c) stable or decreasing.

This is the one I have
http://www.ebay.co.uk/itm/120485600786

sharkbait
Member

i think there was someone on arbtalk who had run a comparison between a high end MM and the £10 version…. he found very little difference.

Stoner
Subscriber

SB – are you going to the Arb show at the Bathurst this year – I was planning on mooching along and stroking some axes etc?

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