CONVEYOR BELT RATING CHART (EP / NN)
Technical Guide
What Does EP 400/3
Actually Mean?
Every fabric conveyor belt carries a rating like EP 400/3 or NN 630/4. The letters tell you the fabric, the first number is the belt’s full-width breaking strength in newtons per millimetre of width, and the number after the slash is the number of plies. This page explains how to read the rating and gives the common combinations in one place. For choosing the belt for a job, also see our belt selection chart.
Reading the Code
| Part of Code | Meaning | Notes |
|---|---|---|
| EP | Fabric type | Polyester in the length (warp), nylon across (weft). Low stretch, good for longer conveyors and wet conditions. |
| NN | Fabric type | Nylon in both directions. Very flexible, good impact resistance, suits smaller pulleys. |
| 400 | Belt rating | Minimum breaking strength of the whole belt, in N/mm of belt width. |
| /3 | Plies | Number of fabric layers in the carcass. |
So a 1000 mm wide EP 400/3 belt has a minimum breaking strength of about 400 × 1000 = 400,000 N (roughly 40 tonnes) across its full width. The belt is never run near that figure – a safety factor is applied, and the joint is weaker than the belt itself.
Common Rating Combinations
The belt rating is roughly the ply strength multiplied by the number of plies, rounded to the standard series.
| Plies | Typical Ratings (EP; NN follows the same series) | Approx. Strength per Ply (N/mm) |
|---|---|---|
| 2 | EP 200/2, EP 250/2, EP 315/2, EP 400/2, EP 500/2 | 100 – 250 |
| 3 | EP 250/3, EP 315/3, EP 400/3, EP 500/3, EP 630/3, EP 800/3 | 80 – 270 |
| 4 | EP 400/4, EP 500/4, EP 630/4, EP 800/4, EP 1000/4 | 100 – 250 |
| 5 | EP 500/5, EP 630/5, EP 800/5, EP 1000/5, EP 1250/5 | 100 – 250 |
| 6 | EP 630/6, EP 800/6, EP 1000/6, EP 1250/6, EP 1600/6 | 100 – 270 |
For the same total rating, fewer, stronger plies give a thinner, more flexible belt that suits smaller pulleys, while more plies give a stiffer belt with better load support across wide troughs and better holding of fasteners.
Cover Grades
The rating tells you the strength of the carcass. The cover grade tells you how the rubber resists wear, heat, oil or fire. Indian standard IS 1891 (Part 1) sets minimum properties for general purpose covers:
| Grade | Tensile Strength, min (MPa) | Elongation at Break, min (%) | Abrasion Loss, max (mm³) | Typical Use |
|---|---|---|---|---|
| M-24 | 24 | 450 | 150 | Heavy, sharp and abrasive material: ore, stone, limestone, coal – see M-24 grade belt |
| N-17 | 17 | 400 | 200 | Lighter, less abrasive duties |
Special duty covers are chosen on other properties: heat resistant belt and ultra heat resistant (UHR) belt for hot material, fire resistant (FR) belt where fire is a risk, oil resistant belt and oil & heat resistant (ORHR) belt for oily material, and SAR grade belt for very high abrasion. Ask for the test certificate with every supply – it states the actual values for your batch.
Cover Thickness
| Material | Top Cover (typical) | Bottom Cover (typical) |
|---|---|---|
| Light, fine, non-abrasive (grain, sand, fertilizer) | 3 – 4 mm | 1.5 – 2 mm |
| Medium lumps, moderate wear (coal, limestone, clinker) | 5 – 6 mm | 2 – 3 mm |
| Large, sharp, heavy lumps (ore, boulders, slag) | 6 – 10 mm | 3 mm |
These are starting points. Loading height, lump size, belt speed and how often the belt passes the loading point all change the answer. If you can share the details in our conveyor belt questionnaire, we will work it out for your conveyor.
Carcass Thickness and Belt Weight
Total belt thickness = top cover + bottom cover + carcass. The carcass is roughly 0.8 to 1.6 mm per ply depending on the fabric strength. To estimate the weight of a belt or the diameter of a roll, use our belt weight calculator.
Get a Quote
Send us the belt width, number of plies, cover thickness and the material you are handling. If you are not sure of the specification, fill our conveyor belt questionnaire and our team will suggest the right belt. Call +91 98275 92612 / +91 90395 92612 or write to info@shrirambeltings.com.
Why Buy From Shriram Beltings?
We make rubber conveyor belts in our own units at Betul (Madhya Pradesh) and Amritsar (Punjab), with a stock depot at Bhiwandi near Mumbai. That means you deal directly with the manufacturer.
ISO 9001:2015 Certified
Every belt is made and checked under an ISO 9001:2015 quality system, so the roll you get next year is as good as the one you got this year.
Ready Stock up to 3200 mm
Popular widths and grades are kept in stock, so breakdown orders can be dispatched quickly. Special sizes, plies and cover thicknesses are made to order.
Right Grade for Your Job
Tell us the material, temperature and conveyor details. We suggest the grade that gives the best life for your money – not simply the costliest one.
Need a Belt? Talk to Us
Call +91 98275 92612 or email info@shrirambeltings.com with your belt size and application. We reply with the price and delivery date.
