MIL-DTL-83528 explained: conductive elastomer EMI gaskets

What the specification covers

The specification sets the general requirements for electrically conductive elastomer shielding gaskets, the parts that close the seam between a housing and its cover so radio-frequency energy cannot leak through the joint [S1]. It is a general specification: the material requirements sit in the base document and the part shapes sit in numbered specification sheets [S3]. The revision history on DLA ASSIST runs from Revision B in July 1992 to the current Revision J, and the preparing activity is DLA Weapons Support in Columbus [S1].

Older drawings and some manufacturer pages still call the document MIL-G-83528; the type letters are the same [S9][S12]. The material tests that manufacturers report against the specification include volume resistivity as supplied, shielding effectiveness in a fixture, resistivity after heat aging and during vibration, fluid immersion and a maximum operating temperature [S10][S14]. The conductive elastomers page explains the fillers behind those figures.

The designation system: type letters and specification sheets

Two codes do the work on a drawing. A type letter names the material, a conductive filler in a base elastomer, and a slash number names the specification sheet that defines the part shape and its size table [S3][S10]. The supplement lists fourteen specification sheets: circular strip (/1), standard O-rings (/2), solid D strip (/3), connector flange mount (/4), non-standard O-rings (/5), rectangular D section (/6), hollow D strip (/7), hollow P strip (/8), solid rectangular strip (/9), channel strip (/10), hollow O strip (/11), flat circular washer (/12), waveguide (/13) and a sheet for time-totalizing meters (/14) [S3]. Manufacturers publish the filler and elastomer behind each type letter, with the limits they quote as the specification's requirement, and those are the rows that follow [S10][S11][S14].

Nickel-plated graphite in silicone carries no type letter in the manufacturer tables, although it is the filler many commercial gaskets use; its published limits are 0.1 ohm-cm and 100 dB at 10 GHz [S10][S11]. Type H is not listed in the manufacturer tables cited here.

The fourteen specification sheets, and how a designation is built

Supplement 1 to Revision E lists the fourteen specification sheets, each one a part shape with its own size table; the custodians on that supplement are Army CR, Navy EC, Air Force 85 and DLA CC [S3]. The rows below name each sheet in our words; the sheet documents themselves carry the tables.

A designation is built from the specification, the sheet, the type letter and a dash number: M83528/001A001 is sheet /1, Type A, size 001, and the QPL parts view runs from /001A001 through /001B012 on its first page [S2]. Laird's extrusion guide prints the equivalent government designation beside each commercial profile with X standing for the type letter, so /001X001 sits beside a 0.040 in solid O and the reader supplies the letter from the material [S11]. The sheet gives the profile and its size table, the letter the material, the dash number the size, and the revision of the base specification governs the tests [S2][S3]. Paragraph numbers shift between revisions: the 2000 handbook cites 4.6.x paragraphs under MIL-G-83528B, Laird cites 4.5.x under MIL-DTL-83528C, and Parker®'s June 2026 guide cites 4.5.9, 4.5.12, 4.5.13, 4.5.15 and 4.5.16 without a revision letter, so a callout that names test paragraphs should name the revision too [S9][S10][S15]. The record runs B, C, D, E, F, G, H, J: there is no Revision A and no Revision I [S1].

How to read a callout on a drawing

A drawing usually gives the specification, the type letter and either a specification-sheet part number or a dimensioned profile. On the qualified products list the government designations take the form M83528/001A001: M83528 for the specification, three digits for the specification sheet, then a letter and a number for the material and the size on that sheet [S2][S3]. So a callout of MIL-DTL-83528 Type B on a solid D strip means silver-plated aluminum in silicone to the /3 sheet profile, and a Type D O-ring means the same filler in fluorosilicone to the /2 or /5 sheet [S3][S14]. If the drawing gives only a type letter and a dimensioned profile, send the profile with the letter and the quantity; the letter fixes the material family and the profile fixes the part.

Watch for two things when you read an old drawing. MIL-G-83528 and MIL-DTL-83528 are the same document under its earlier and current prefix, so the type letters carry over [S9][S12]. A revision letter on the callout, such as MIL-DTL-83528G, dates the drawing; the active issue is Revision J, and DLA ASSIST is the place to confirm which issue applies to your contract [S1].

What QPL qualification means and where the list lives

A qualified products list, or QPL, records the products and the manufacturers that passed a specification's qualification tests before any contract is awarded, so a buyer can order against the specification without repeating those tests. DLA maintains QPL-83528 in its Qualified Products Database; the parts view listed 32,911 government designations across 1,317 pages when we checked it, last updated 7 May 2026 [S2]. Each row carries the government designation, the national stock number where one exists, the specification sheet and a critical-safety-item flag [S2]. Check the source list on the database itself before you specify a source, because qualifications are added and withdrawn over time [S2]. The database's governing entry for QPL-83528 read MIL-DTL-83528C with Supplement 1A (2001) while ASSIST lists Revision J (2023) as current; the two records disagree, and ASSIST is the record of the current issue [S1][S2].

Nine suppliers held QPL-83528 qualification on the DLA Qualified Products Database on 2026-09-14, every one listed as a manufacturer in the USA, by CAGE code: 02GM4 Specialty Silicone Products Inc; 18565 Parker-Hannifin Corp; 27565 Nolato Jabar LLC; 4J674 Leader Tech Inc; 4L975 SAS Industries Inc; 4VDV9 East Coast Shielding LLC; 65219 Seal Science Inc; 6R663 Vanguard Products Corp; 77969 Rubbercraft Corp of California Ltd [QPD-1]. That is the public record on the day it was read; the list changes, so check the database before you specify a source [QPD-1][S2].

A QPL names manufacturers and their qualified materials, never distributors, and Conquest Seal is not on it. Conquest Seal sources conductive elastomer from QPL-listed manufacturers, and when your drawing requires a qualified source the quote names the manufacturer whose material is quoted against the type letter and the sheet number.

EMI shielding and environmental sealing in one gasket

A conductive elastomer gasket does two jobs: it keeps the joint between two flange faces electrically continuous, and it seals the same joint against water, dust and pressure [S10][S13]. Both jobs depend on deflection, the change in gasket height under the closing load, and manufacturers publish a working range per profile: 5 to 10 percent for flat strip, 20 to 25 percent for a solid O section, 15 to 20 percent for a solid D and up to 50 percent for hollow sections [S10]. Fluorosilicone Types C and D are the ones that survive the specification's fluid immersion test; the silicone Types A, B and M do not [S14]. Where the gasket also holds pressure, the groove bottom needs a finish of 32 to 64 microinch RMS and the groove must leave enough room that the gasket never fills more than 95 percent of it [S9].

Corrosion at the flange is the other half of the environmental question, and it decides the filler as much as the shielding figure does. The conductive elastomers page covers galvanic pairing with aluminum, salt fog and temperature; the conductive O-ring page covers groove dimensions for round sections.

Specifying an EMI gasket for a military enclosure

Seven items on the drawing or the request let a supplier quote the right part without a second round of questions.

1. The specification and its revision: MIL-DTL-83528, Revision J at the time of writing [S1].
2. The type letter, or the filler and base elastomer if the drawing is commercial [S10][S14].
3. The specification sheet and dash number, or a dimensioned profile with the free height and width [S3].
4. The flange metal and its finish; chromate conversion coatings on aluminum count as conductive finishes in the manufacturer's guidance [S9].
5. The environment: salt fog, fuels or oils, and the temperature range, against the -55 C minimum and the 125 C or 160 C maximum by type [S14].
6. Whether the contract requires a source that appears on the QPL [S2].
7. The quantity and any first-article or certification paperwork the order needs.

Send those with the drawing and Conquest Seal quotes the material against the type letter. Flat gaskets are cut from conductive silicone sheet to your drawing on our waterjet; see the conductive silicone sheet page for the fillers and thicknesses, the design guide for the groove, and the testing guide for what the shielding figure means, or go straight to the request a quote form.

Spec values on this page come from the sources below; the specification text itself is not reproduced here. Check DLA ASSIST for the issue that applies to your contract.