Bimetal Thermometers

IPE Engineering Practice IPE-EP-12-1-8

Document number: IPE-EP-12-1-8 · Section: 12 — Instruments and Controls

SCOPE

Dial type indicating thermometers shall be supplied in strict accordance with the Data Sheet, this Practice, and the referenced standards and publications.
Where special features or improvements over the Practice are required as determined by the Owner, or Owner’s Engineer, these shall be specified on the Instrument Data Sheets and shall be adhered to by the Vendor.
Any deviation from this Practice must be approved by the procedure described in EP 1–1–3.
A revision bar indicates all changes made to this Revision.

2.0 REFERENCES

The following codes and standards shall be considered as part of this Practice. All documents shall be the latest editions in force on the date of issuance of this Practice.

STANDARDS AND PUBLICATIONS

IPE Engineering Practices
EP 1–1–3 Deviations to IPE Engineering Practices EP 12–1–1 Control Systems EP 12–1–2 Supplemental Requirements for Control Systems EP 12–1–6 Primary Temperature Element Assemblies
ASME
B 1.20.1 Pipe Threads General Purpose (Inch)

DEFINITIONS

Contractor - Company or business that agrees to furnish materials or perform specified services at a specified price and/or rate to the Owner.
Inspector - A Inflection Point Engineering, LLC . appointed engineer or inspector.
Manufacturer - The recipient of a direct or indirect purchase order for materials and/or equipment. In this context, a direct order is one issued to a manufacturer by a contractor or the Owner. An indirect order is one issued to a manufacturer by a vendor (recipient of a direct order) for materials, fabricated components, or subassemblies.
Owner - Inflection Point Engineering, LLC .
Owner’s Engineer - A Inflection Point Engineering, LLC . appointed engineer.
Purchaser - The party placing a direct purchase order. The purchaser is the Owner’s designated representative.
Vendor - Recipient of a direct purchase order.

DESIGN AND MATERIALS

General
The thermometer case shall be Type 304 stainless steel. Other components of the thermometer and the materials thereof shall be of the manufacturer’s standard unless otherwise specified, and shall be adequate for the operating conditions specified in the Data Sheet.
Under static temperature conditions, the permissible deviation of the indicated temperature from the true temperature of the sensitive portion of the protector tube shall be limited to 1% of the scale span.
Thermometers shall be factory calibrated.
Thermometers shall have external zero adjustment.
Primary Element
The primary element shall be capable of withstanding, without damage or change in calibration, the lesser of either 800oF or a temperature equal to 150% of the maximum scale value. The element shall be arranged to actuate an indicating pointer.
Bi-metallic elements shall be either a continuous wound multiple helix, or a single helix contained in dampening fluid.
Case and Dial
The thermometer shall be of weatherproof construction heavy duty suitable for either indoor or outdoor installation.
The thermometer case shall be appropriate for back type of stem connection unless otherwise specified on the Data Sheet.
All process thermometer dials, shall be a minimum of 5 inches in diameter with a non-glaring white finish and black numbers. Process thermometers shall have every angle stem connection.
Protector Tube
The helix (temperature sensitive section) shall be enclosed within a type 304 seamless steel protecting tube of the length specified on the Data Sheet. The length specified shall include the threads for connection into the thermowell.
The tube shall be 1/4 inch OD and shall be provided with 1/2 inch NPT external threads conforming to ASME B1.20.1. The tube shall have a hexagonal head or wrench flats and shall fit within a 0.260 ” 0.005 inch ID thermowell.
Thermowell
Thermometers may be furnished with a thermowell. The Vendor shall be responsible for fitness of the thermometer/well assembly when supplied.
Thermowell type, construction, and materials shall be in accordance with the Data Sheet. Thermowells shall be drilled bar stock type. Built-up types are not acceptable.

5.0 INSTRUCTIONS FOR DATA SHEET

The following numbers correspond to the line numbers on the Data Sheet:

Specify mounting termination of stem and write in stem materials or ”MFR.STD.
Select stem thread size
Stem diameter standards may vary.
Write in case material if other than standard
Write in nominal dial size and color
Scale length
The form of the thermometer is illustrated on the form. The adjustable form may be set to any angle. If a stem connection form other than shown is required, make a sketch in the space provided.
Check applicable options
List specific make and model number when selection is made
Specify how well is to be furnished, if any
Specify well material. If not all are the same, cover exception by notes in the tabulation.
Specify well construction. Special well design should be described by a sketch in the space provided or on an attached sheet.

Tabulation:

Tag No: It is assumed that a tag number represents a single item. If multiple units have the same number, cover this with a special note.

Range: Write ”F” or ”C” at the top of the column. May be left blank on initial issue of Operating Temp is specified.

Operating temp.: Must be filled in if range is not specified. Stem length: Refer to illustrations on form.

Well Conn: Show thread size, such as ”1 inch NPT” or flange size and rating. All flanges are assumed to be ANSI Standard, if not, cover by a special note.

Lag. Ext: Applies to screwed wells only

Notes: Index notes by number or letter and specify in space below tabulation.

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