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Picked up a couple of interesting pieces the other day

Brian Manning

Registered
That mag charger is a beauty. Does it have a manufacturers tag?
Harvey, unfortunately no there is no identifying marks or tags on the charger anywhere. I'm sure if you have a pace maker you don't want to be any here near that when you turn it on:yikes:
The dead weight tester does ,interestingly enough, have a tag on it, RCAF-Ref6C/521, so one of volunteers son works for NDN and he came up with some interesting history on it. It is a well known Type 452 made by Amthor Instruments, and was sold (or resold) by Canadian Applied Research Ltd. a company related to AV Roe, of Avro Arrow fame, and which eventually became SPAR Aerospace. It was found to be properly disposed of by the Director General Marine Equipment Program Management. So whats something that flies, but reports to the Navy? Along with the RCAF number it also has a date tag of 11-09-59, and was traced back as being used to support the CT-133 Canadair Silver Star. The date is relevant as that was the date the Silver Star trainers were handed over to the Turkish Air Force as part of Operation Western Weal. The aircraft would have been used by the RCN (Royal Canadian Navy) as the Silver Stars were used as trainers by the RCN from 1955-2002.
Now it gets interesting because a squadron of Silver Star trainers were based out if Cold Lake Alberta, as well as others across the country, and we have 2 of the aircraft in our collection. The tail numbers are in the same group of aircraft so this tester has a good chance of being tied to them.
Both pieces came from a collector in Edmonton with a aviation background.
 

Harvey Teal

Subscriber
Last Subscription Date
07/22/2019
Harvey, unfortunately no there is no identifying marks or tags on the charger anywhere. I'm sure if you have a pace maker you don't want to be any here near that when you turn it on:yikes:
The dead weight tester does ,interestingly enough, have a tag on it, RCAF-Ref6C/521, so one of volunteers son works for NDN and he came up with some interesting history on it. It is a well known Type 452 made by Amthor Instruments, and was sold (or resold) by Canadian Applied Research Ltd. a company related to AV Roe, of Avro Arrow fame, and which eventually became SPAR Aerospace. It was found to be properly disposed of by the Director General Marine Equipment Program Management. So whats something that flies, but reports to the Navy? Along with the RCAF number it also has a date tag of 11-09-59, and was traced back as being used to support the CT-133 Canadair Silver Star. The date is relevant as that was the date the Silver Star trainers were handed over to the Turkish Air Force as part of Operation Western Weal. The aircraft would have been used by the RCN (Royal Canadian Navy) as the Silver Stars were used as trainers by the RCN from 1955-2002.
Now it gets interesting because a squadron of Silver Star trainers were based out if Cold Lake Alberta, as well as others across the country, and we have 2 of the aircraft in our collection. The tail numbers are in the same group of aircraft so this tester has a good chance of being tied to them.
Both pieces came from a collector in Edmonton with a aviation background.
It’s a real blessing to see an instrument that has been cared for. No doubt it could last for another hundred years and be just as accurate as new. Of course now you’ll need to use it, maybe get in to contract testing.....
 

Brian Manning

Registered
It’s a real blessing to see an instrument that has been cared for. No doubt it could last for another hundred years and be just as accurate as new. Of course now you’ll need to use it, maybe get in to contract testing.....
Yup, that's the plan.👍 Although we won't be going into the gauge re-calibration business, I do intend on using it on the gauges already in use and any other that are in storage as they are required. Following ABSA's regulations for Historical boilers we will still have to have a certified calibrated test gauge for hydro's.
 

Harvey Teal

Subscriber
Last Subscription Date
07/22/2019
Yup, that's the plan.👍 Although we won't be going into the gauge re-calibration business, I do intend on using it on the gauges already in use and any other that are in storage as they are required. Following ABSA's regulations for Historical boilers we will still have to have a certified calibrated test gauge for hydro's.
What is the desired pressure range of the gauge that you plan to use for hydros?
 

Gauge Man

Registered
Normally, or the rule of thumb is, a Pressure Gauges pressure range should selected at twice the normal working pressure. So if your normal working pressure is 100 psi you should use a pressure gauge with a scale range of 0 to 200 psi.

Although a pressure gauge can and will work to it's full scale range accurately to the manufactures stated accuracy specifications with out any real short term effects the reasons not to are as follows.

1) This 50% of full scale rule or 10 to 2 o'clock range is the optimum manufacturers design on the bourdon tube in the gauge. The amount of stress or stretching that is applied to the metal bourdon tube is to keep the gauge within is manufactures stated accuracy specifications longer. If you cycle the pressure to the tube to full scale, over time it will shorten the life of the gauge because you are bending the metal tube to its maximum. The metal tube will fatigue and causes the tube to develop a stress crack on the edge of the tube and it will leak your process media. Also with this fatigue the tube will begin to stretch before it cracks and cause the gauge to drift out of calibration.

2) It is generally accepted that a gauge is more accurate in the middle 1/3 of the scale range but not always so. Many of today's industrial grade (ASME B40.1 Grade 1A or better) have a ± % of full scale accuracy rating. Example: a 0 to 100 psi gauge with a Grade 1A, is a ±1.0% accuracy of full scale will be accurate to ±1.0 psi over the entire scale range making it the same over the complete range of the gauge. When you drop down to a "Grade B" or less these gauges accuracies are stated as ±3-2-3%. This means that the gauge is accurate to ±3% of full scale in the (First ¼ and Last ¼) of the scale and are accurate to ±2% in the middle half of the scale. As a person who calibrates pressure gauge I always try to make sure the gauge is most accurate in the center or 12 o'clock of the scale but I can not always do this on 100% of the gauges that I calibrate. However, the gauge will always be calibrated within the stated manufactures accuracy, if not the gauge does not pass, the gauge fails and is scrapped.

3) Another reason is for the operator. If the pointer is always pointing in the 12 o'clock area, or maybe somewhere in the 10 o'clock to 2 o'clock range the operator will not have to read the gauge but just glance at it and can easily see that the pointer it in within the normal working range. If he sees the pointer out of this mid-scale area this should alert him to a possible problem in the system. This should be the same for all the pressure and temperature indicators in the plant. Now you know why a drag strip race car driver has his tachometer twisted with his red line at 12 o'clock or sometimes 6 o'clock, he doesn't have time to read it, he knows when the pointer hits 12 o'clock he needs to shift gears.

See attached ASME B40.1 Gauge Accuracy Chart.

Temperature will also effect accuracy of a gauge.

I welcome your questions.

Stay
 

Attachments

Harvey Teal

Subscriber
Last Subscription Date
07/22/2019
In this month's Gas Engine Magazine (April/May 2020) there is a twelve page article by Peter Rooke about both designing and building a mag charger. Very interesting read.
That charger has inspired me to build one last charger. The coil forms willl be G10 fiberglass epoxy. The outer jacket will be epoxy/carbon fiber if I can verify that this will be nonconductive. The base will be styled to look like Brian’s rig. Hope the current price of Copper has fallen a bit....
 

Vanman

Subscriber
Last Subscription Date
07/10/2019
That magnet charger is neat for sure, but one could easily build one in their shop. That dead weight gauge tester on the other hand is stunning! Imagine the effort required to build one of those! I am fortunate to have a friend with one for all of my gauge testing needs. ;)

Keith
 

Harvey Teal

Subscriber
Last Subscription Date
07/22/2019
That magnet charger is neat for sure, but one could easily build one in their shop. That dead weight gauge tester on the other hand is stunning! Imagine the effort required to build one of those! I am fortunate to have a friend with one for all of my gauge testing needs. ;)

Keith
An accurate dead weight tester, like a functional magnet charger, can be built in a few hours. To do a spectacular job requires time, patience, and an eye for detail. David Pye discussed this concept in his publications: The Nature and Aesthetics of Design and The Nature and Art of Workmanship. It’s refreshing to see that somebody did indeed take the time to do it right. Good find, Brian...
 
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