Understanding the Murphy Compensation Cup

[Bruce L]

First time using last night,was trying to get the red line on the hydrometer lined up with the red line on thermometer,where exactly should everything be for syrup coming right off the evaporator,219+ degrees? Thanks

[Super Sapper]

First fill the Murphy cup and then add the hydrometer. Let is sit for a little bit to stabilize the temp. If you at syrup your hydrometer will match the dial reading on the Murphy cup. If the murphy cup says 63 and your hydrometer says 61 you are 2 points low and will need to boil it some more to get it to syrup. It the Murphy cup says 63 and your hydrometer says 65 you will need to dilute the syrup with sap or water until the 2 match. Do not worry about the red lines on the hydrometer.

[sugarsand]

I boiled most of my life with just a hydrometer till we bought a Murphy cup when it came out, it makes getting syrup right that much easier, especilly during a slow draw and the drawn syrup temps have cooled down giving you a false reading with just a hydrometer.

[maple flats]

The beauty of the Murphy cup is that you do not need to know the temperature of the syrup. The Murphy cup tells you what the reading should be for proper density syrup.

[Bruce L]

Thanks for the help,will have a better idea of getting it dialed in next boil. Had the instructions out but forgot to take them down to the sugar house,and assumed I had to hit the two red marks,hence I set the Marcland at 219.6 ,so now my 20+ gallons of golden syrup is reading 69.5 How much distilled water do you add to bring the syrup down to 67 or slightly under,and do you have to heat over 180, where nitre might occur? Thanks

[johnallin]

Bruce - 2.5 oz of water/gallon for a 1% reduction.

[wmick]

Does anyone have a first hand comparison between using the Murphy cup and a "Hydrotherm"?
I've been attempting to use hydrotherms... and not terribly happy with them.. Seems to take a long time for temperature compensation to catch up or something...

I purchased a refractometer this year, but I think this Murphy Cup might be something to try out.

[maple flats]

I never used a hydrotherm but I used to use an accu cup that gave the temperature of the syrup then consult a chart on the wall to see what the density should be at that temperature. The big problem there is that the chart does not give the density for each degree, if your temp was between 2 readings on the chart you had to guess what it should read.
Then along came the Murphy cup. It is really just a thermometer with the face changed to give the density at that temperature, fast , accurate and best of all no guessing. It is calibrated for Vermont's std, which is 66.9%, but I used that before the Murphy cup so no issue even though in New York I could use 66.5%.

[marlmucker]

Anyone know if and where these can be purchased in Canada?

[Bruce L]

Anyone know if and where these can be purchased in Canada?
I ordered mine directly from Smoky Lake,don’t think you will find them anywhere else

[Bruce L]

Bruce - 2.5 oz of water/gallon for a 1% reduction.

Thanks John

[johnallin]

I never used a hydrotherm but I used to use an accu cup that gave the temperature of the syrup then consult a chart on the wall to see what the density should be at that temperature. The big problem there is that the chart does not give the density for each degree, if your temp was between 2 readings on the chart you had to guess what it should read.
Then along came the Murphy cup. It is really just a thermometer with the face changed to give the density at that temperature, fast , accurate and best of all no guessing. It is calibrated for Vermont's std, which is 66.9%, but I used that before the Murphy cup so no issue even though in New York I could use 66.5%.

I also had an Accu Cup and - other than the stiff neck I'd get from constantly turning my head to look at the temp conversion chart on the wall - liked it a lot.
(you'd think I could remember that at 195° the hydro would float at the 62½ line?)
The Murphy cup changed all of that just like Dave said. What a great gadget.
Bruce you'll be amazed at how much easier this is. Just be sure to calibrate with ice water and adjust to 32° if needed.

[toothfairy050]

Just remember to calibrate the Murphy before using it.

[Sugarmaker]

I have not calibrated mine. I guess I should do that. I like the fact that drawn syrup if drawn can be quickly adjusted to get the correct density. The thing that clicked with me was the instructions say look at the dial on the cup first and that is the target for the hydrometer. The red line on the hydrometer is only a reference to the old way of using hydrometer.
Regards,
Chris

[Bruce L]

I also had an Accu Cup and - other than the stiff neck I'd get from constantly turning my head to look at the temp conversion chart on the wall - liked it a lot.
(you'd think I could remember that at 195° the hydro would float at the 62½ line?)
The Murphy cup changed all of that just like Dave said. What a great gadget.
Bruce you'll be amazed at how much easier this is. Just be sure to calibrate with ice water and adjust to 32° if needed.

Okay now you have me confused about the ice water,fill the cup and adjust the thermometer somehow,is the hydrometer also needing calibration?

[Sugarmaker]

You can have the hydrometer tested for correctness but it can not be calibrated.
Regards,
Chris

[Bricklayer]

I’ve had my Murphy cup from smoky lake for 3 years now and just for fun a couple time’s I tested the temperatures relative to the cup reading on the dial. They give you a chart with the cup when you buy it. In case you need to calibrate it. Has been spot on every time. Never needed to adjust anything.
Bruce, did you get a hydrometer from smoky lake as well? One thing I did notice is hydrometers in Canada and the US are calibrated at different temps. So I found that using the smoky lake one works the best.
I wouldn’t worry to much about calibrating a brand new Murphy cup. I don’t even take any of my old hydrotherms or hydrometers or digital refractometers out of the tote anymore. They are retired. Once you start comparing readings and second guessing one or the other it just gets you doubting all your devices. We have all had this happen. You’ve got the right tool now. Will give you great readings every time.
I do a lot of testing right off the draw off when I’m drawing off. And with piping hot syrup right off the draw off if it’s between 59-60.5 on the temp dial within 15 seconds the temp dial is working just fine.

[pete3046]

I only have experience with the murphy cup this year, but there is one item that I noticed. When I get ready to bottle, I start using the murphy cup for the cold temp check, 60deg F, and I always seem to read that I’m heavy, sometimes really heavy on my hydrometer. As the syrup gets up to bottling temperature, even up to the hot check at 212deg F, I start to get much lighter hydrometer readings, even alignment of the cup to the hydrometer. Last week I had 5gal of syrup and I started to thin it out based on the lower temperature murphy cup reading, as I was heavy, and by the time I got up to the bottling temperature, I has light on the hydrometer, too light! So, I needed to boil off a little in my bottling kettle, which is not so fun! Last night I went through the same exercise with 3gal of syrup and the same readings occurred, heavy on the hydrometer at lower temperatures, and lighter on the hydrometer at higher temperatures. Last night I waited until I drew a high temperature reading, at 212deg, prior to thinning and it worked out fine.

Oh, it is also worth noting that I do try to draw-off a little on the heavy side from my evaporator. Although, I’m still working to get that end right. Once I start to draw-off, I keep a small stream running shutting down my draw-off for wood reloads and then restarting based more on feel than an actual murphy cup reading!

Thanks,
Pete

[DrTimPerkins]

Have you calibrated the Murphy cup recently according to the instructions?

[wmick]

I’ve had my Murphy cup from smoky lake for 3 years now and just for fun a couple time’s I tested the temperatures relative to the cup reading on the dial. They give you a chart with the cup when you buy it. In case you need to calibrate it. Has been spot on every time. Never needed to adjust anything.

I find this surprising.... As I understand it... a "Murphy Cup" is just a thermometer with a different scale and numbers printed on it to match the hydrometer charts.
This being the case.... I would think it would need calibration often, due to barometric changes?. I find that my thermometer can need adjustment every day or even throughout the day, depending on the pressure change..

[ecolbeck]

Only the boiling point of water changes with barometric changes. Temperature and density remain constant.

[wmick]

Only the boiling point of water changes with barometric changes. Temperature and density remain constant.

Hmm? Yes - I see what you mean...
Took a little head scratching for a minute.. but I think I have my head wrapped around it.

When I calibrate my thermometer, I am just adjusting it to match the boiling temperature of water, (which is not necessarily 212)... in order to have a reference for 7 degrees hotter for syrup..(which is not necessarily 219).

So for use with a hydrometer, I should want to use a thermometer that is calibrated for absolute temperature...(not compensated for boiling)
(But being that a 1% change in Brix is equal to about 19 degrees difference in temp, on the smokey lake hydrometer chart... A thermometer would need to be off quite a bit to make a significant error).

[Bricklayer]

the First couple times I used it I would do a test. Then leave the syrup in the Murphy cup with the hydrometer for a while.
Maybe 10 minutes. And the readings would be different then the original first reading at say 25-30 seconds.
I contacted smoky lake and inquired about it. You would think as the temp goes down the hydrometer would as well. But they told me for best results take the reading in the first 30 seconds when the temp gauge stops moving. . So now that’s how I do it. If it sits for any longer then a minute I test a new sample.
I tested my Murphy cup last night with water and 3 thermometers and the temp gauge on the Murphy cup was still bang on accurate. I did notice as the water cooled that the digital thermometer was quicker to respond then the Murphy cup. So this is maybe why the readings as the syrup cools down are not accurate if left in syrup as it cools.

[ashadedacre]

Curious if there is anyone in Ontario or even Canada to get that Murphy Float. Smoky Lake isn't shipping to Canada at the moment.

[randolphvt]

What I recall is boil water and take the temp. Not everyone is 212. I'm 213 due to 740ft of elevation-so 220 for me. It's always 7 over boiling point of water where you are.

[randolphvt]

Oops I think I replied to the first post and not the last. Sorry.