Pressure Gage Testing Apparatus

Pressure Gage Testing Apparatus

gauges; steam engineering; mechanical engineering; boilers

Physical Description

A brass pressure gauge testing apparatus kit inside a fitted wooden case. The kit consists of a wooden base, brass cylinders, a reflective metallic weigh plate, four bolts, an oil pan, two notepads, and a steel wrench.

The main brass body of the instrument is composed of 3 cylinders: 1) a main upright cylinder with threaded cap that is removed to insert the weigh plate; 2) an L-shaped arm with a horizontal cylinder perpendicular to the main one whose diameter varies by about 10mm and a 90° upward bend, terminating in a threaded opening; and 3) an upright diagonal cylinder that has a threaded adjustment arm within for adjusting pressure inside the apparatus during the testing of a pressure gauge. The L-shaped arm has a valve release knob on its horizontal portion and a threaded top on its vertical portion where a threaded pressure gauge attaches.

The rest of the kit is organized in engineered slots for all of the components. The instrument fits snugly within the wooden case, the metallic weigh plate is held in place on the wooden kit base with 3 adjustable wooden pegs. Four pressure gauge adapters for different thread combinations fit into four wooden holes to the right of the wooden kit base, and the oil pan fits just underneath an oil release valve on the horizontal portion of the L-shaped arm. In addition, notepads and a wrench are kept in the case, but without dedicated spots.

The wooden case itself has a single metal latch on the front face and a handle on the top. It is marked with a Michigan College of Mining and Technology property tag underneath the latch that reads “MCMT-1 741 1” ,which places the date of acquisition of this instrument between 1925 and 1967, the period in which out university bore that name. (A paper tag that reads “5” attached with cellophane tape is presumably just a collection number for the MEEM department records).

There are several inscriptions engraved on the instrument. On the top of the wooden base at the rear there is “1073” likely indicating a production number, the 1073rd apparatus to come out of production from Crosby Steam Gage & Valve Co. On the main upright cylinder is engraved “PAT. MAR 11 1884”, signifying the date a U.S. patent was granted. On the knob of the perpendicular cylinder, “DRAIN” and “OPEN” are on the flat faces to signify the position on the internal drain valve. “X” appears on both of the small side faces of the knob to signify the stoppage of oil flow. The inside face on the spout of the oil pan also has an engraving “PAT. U.S.A. DEVERALL’S”, signifying the producer of the pan.

Functional Description

The instrument is intended to be attached to pressure gauges on steam engines and other steam machinery with pressure gauge displays to test their accuracy.

To properly use the instrument, one would unscrew the cap on the main upright brass cylinder and insert the metallic weight plate. Then, they would select one of the four adapters that matches the threading type and size (they take the ¾-16 thread to either 13mm(male), 13mm(female), 9mm(female), or 4mm(male)) of the pressure gauge to be tested and screw that into the receptacle at the end of the L-arm. The kit-provided wrench may be used to tighten the bolt, and a weight (not included with the kit) would be placed on top of the metallic weigh plate. The threaded adjustment arm in the diagonal cylinder would then be screwed in or out to bleed off the appropriate amount of pressure as to not launch the weigh plate off of the apparatus, and the pressure gauge would then be screwed into the aforementioned bolt on the perpendicular arm to begin testing. The results would then be recorded on the provided notepad. Oil that collects inside the apparatus from the steam is periodically drained into the provided pan and refilled as necessary to prevent pressure buildup or malfunction in the instrument.

It is not known the methods for which the threaded pressure adjustment arm in the diagonal cylinder are properly used, as there are no provided instructions or documentation with the instrument or available in records online. It can be assumed that the calculations for how much pressure to release when testing are able to be performed by hand based on the amount of pressure the gauge being tested is responsible for.

Peyton Hall

c.1884

physical object

English

MTU (MCMT) property tag 17411. MEEM Inventory #5

United States of America

[Box] 381mm(w), 246mm(h), 216mm(d); inside: 11in(w), 8.5in(h), 7.25in(d)
[Base: 273mm(w), 21mm(h), 180mm(d)
[Pressure Apparatus] base: 100mm diam.; primary arm: 82mm(h) with 40mm cube joint; perpendicular arm: 100mm(l), 60mm(h); diagonal arm: 150-220mm(l), 35mm diam. (without bolt).
[Oil Well: 76mm/3in(w), 42mm(h), 76mm/3in(d); spout: 30mm(diameter), 42mm(h)
[Disc: 144mm/4.5in(diameter), 4mm(h); Disc Shaft: 17mm(diameter), 90mm/3.5in(h)
[Bolts: 5mm(diameter, all male ends), 13mm(male, bolt 1), 13mm(female, bolt 2), 9mm(female, bolt 3), 4mm(male, bolt 4)
[Notepads] 3in(w), 7in(h)
[Wrench] 47mm(w), 13mm(h), 115mm(d)

Brass, wood, steel, paper, oil

Crosby Steam Gage & Valve Co., Boston, MA

[Base] 1076
[Main Upright Brass Cylinder] PAT. MAR 11, 1884
[Perpendicular cylinder knob] OPEN | DRAIN | X | X
[Oil Pan] PAT. U.S.A. DEVERALL’S

MEEM (3rd Floor Display Case)