CMP 737 Thread Adaptors and Reducers for Explosive Atmospheres

Thread conversion for Ex enclosures with the wrong entry size

The CMP 737 range of adaptors and reducers converts the entry thread of a cable gland or accessory to match the thread of an explosive atmosphere enclosure. An adaptor steps a male thread up to a larger female thread (up to two sizes), while a reducer steps a larger male thread down to a smaller female thread. Both are globally approved and available in brass, nickel plated brass, stainless steel, aluminium and nylon for a wide range of metric and NPT sizes.

Conversions are common when a gland of one thread standard has to fit equipment from another, for example a metric gland into a NPT-threaded enclosure on imported skids and packages. The metallic versions are rated from -60 to +200 C, with IP66, IP67 and IP68, and the datasheet offers an optional equipment-interface o-ring seal and a general purpose (industrial) version.

Technical specifications

Examples from the dimension tables (the full table maps each male and female thread to a reference code):

How to select an adaptor or reducer

The datasheet uses a three-step method. Select the male thread in the left column of Table A, select the female thread across the top, and read the reference (A for adaptors, R for reducers); then look up the across-flats, across-corners and minimum bore in Table B. When ordering state the male thread first, as in 737-D-M-2-M-3-4 (M20 male to M25 female, stainless steel, dual certified).

The datasheet gives basic engineering rules for Ex use: for direct entry Ex d applications only one adaptor or reducer should be used per cable entry, and the female thread of an adaptor shall step not more than two sizes up when changing gender (for example M20 male to M32 female or to 1 in NPT is permitted, whereas M20 male to M40 female is not). Always notify CMP if alternative approval markings are required.

Installation notes

Check the thread form and length at both ends, the sealing of the interface (the optional o-ring) and the overall protrusion into the enclosure. Ex d enclosures have thread engagement requirements, and any thread conversion must keep the certified flameproof joint intact; follow the equipment manufacturer’s instructions. Metallic parts handle the full temperature range while nylon parts are restricted to -20 to +60 C.

How the CMP 737 works

An adaptor has a male thread on one side and a larger female thread on the other. A reducer does the opposite and steps a larger male thread down to a smaller female thread. Fitted between the gland and the enclosure, it matches two different thread sizes.

Where the 737 is used

• Metric gland into a NPT-threaded enclosure
• Imported skids and packages
• Enclosures with the wrong entry size
• Cable gland and accessory conversion
• Mixed thread projects

Selection checklist for the 737

• Adaptor or reducer
• Male thread size
• Female thread size
• Metric or NPT
• Material
• Seal option
• Industrial or hazardous area version
• Ordering code

Installation, commissioning and maintenance notes for the 737

Check the thread type and size on both parts before fitting. Screw the part in fully and tighten it with a suitable spanner. Inspect the threads and any seal at regular intervals.

Requesting a quotation for the CMP 737

Please send the male thread, the female thread and the material needed. Seven Star LLC serves industrial customers in Oman and the GCC and replies with a quotation based on the information provided.

737 product type

It is a range of thread adaptors and reducers.

737 maker

It is made by CMP Products.

737 purpose

It converts an entry thread to match an enclosure thread.

737 adaptor function

An adaptor steps a male thread up to a larger female thread.

737 adaptor step

An adaptor can step up by as much as two sizes.

737 reducer function

A reducer steps a larger male thread down to a smaller female thread.

737 brass

Brass is one of the available materials.

737 nickel plated brass

Electroless nickel plated brass is available.

737 stainless steel

Stainless steel is available.

737 aluminium

Aluminium is available.

737 nylon

Nylon is available.

737 metric sizes

Metric threads run from M16 to M100.

737 NPT sizes

NPT threads run from 1/2 in to 4 in.

737 temperature range

Metallic versions are rated from minus 60 to plus 200 degrees C.

737 nylon temperature range

The nylon version covers minus 20 to plus 60 degrees C.

737 seal option

An optional equipment-interface o-ring seal is offered.

737 industrial version

A general purpose version is available for industrial use.

737 ordering example

The code 737-D-M-2-M-3-4 describes an M20 male by M25 female part in stainless steel.

737 dimension tables

The table maps each male and female thread to a reference code.

737 reducer R03

The R03 reducer measures 30.0 mm across flats.

737 reducer R06

The R06 reducer measures 37.6 mm across flats.

737 reducer R01

The R01 reducer measures 24.0 mm across flats.

Fitting records for the 737

Record the thread sizes, the material and the gland tag it serves.

Choosing the right 737 part

Choose an adaptor or a reducer from the gland thread and the enclosure thread.

Documents and quotation

The attached CMP 737 datasheet includes the how-to-order guide and the full dimension tables for the reducer and adaptor codes. When requesting a price, tell us the size code, entry thread (metric or NPT), material, cable type and construction, hazardous area classification and quantity, and whether shrouds or other accessories are needed. See also Electrical Tapes and Cable Accessories and the CMP Zenith 2BCAL cable cleat for cable support.