# Presentation: 692180

## CONVEYOR BELT FLAMMABILITY

**by**
**Harry Verakis**
**MSHA Technical Support**

## OVERVIEW

***EARLY HISTORY -- FLAME RESISTANT CONVEYOR BELTS***
***FLAME TEST SPECIFIED***
***REQUIREMENT BY 1969 CMH&S ACT***
***PRESENTLY REQUIRED FLAME RESISTANT TEST***
***PROGRAM UNDERTAKEN TO IMPROVE BELT FIRE SAFETY***
***STUDY ON LARGE-SCALE BELT FIRE TESTS***

## OVERVIEW

***DEVELOPMENT OF NEW LABORATORY SCALE BELT FLAMMABILITY TEST***
***VOLUNTARY TEST PROGRAM USING NEW TEST ***
***PROPOSED RULEMAKING FOR A NEW BELT FLAME RESISTANCE TEST***
***PROPOSED RULE WITHDRAWAL ***

## EARLY HISTORY—FR BELTS

**1950’S RESEARCH WORK BY THE BUMINES**
**DEVELOPMENT OF A SMALL-SCALE FLAME TEST**
**NO REGULATION REQUIRING FLAME RESISTANCE CONVEYOR BELT**
**SUBSEQUENTLY, SCHEDULE 2G PROMULGATED (1968) WHICH INCLUDED TEST FOR FLAME RESISTANT CONVEYOR BELT**
**THUS, 2G FORMAL BELT FLAME TEST PROGRAM & ACCEPTANCE LISTING INSTITUTED BY THE BUMINES**
**SCHEDULE 2G DID NOT MANDATE THE USE OF FLAME RESISTANT CONVEYOR BELT**

## 1969 CMH&S ACT

**Section 311(h) of the Act mandated “...all conveyor belts acquired for use underground shall meet the requirements to be established by the Secretary for flame-resistant conveyor belts**

## Title 30, Code of Federal Regulations

**Pursuant to the 1969 Act, Part 75, Section 75.1108 was promulgated and mandated that “On and after March 30, 1970, all conveyor belts acquired for use underground shall meet the requirements to be established by the Secretary for flame-resistant conveyor belts.”**

## Part 75, Section 75.1108-1

**Section 75.1108-1 specified “Conveyor belts which have been approved as flame-resistant by the Bureau of Mines under Part 18 of this chapter (Bureau of Mines Schedule 2G) meet the requirements of  §75.1108.”**

## Part 18, Section 18.65

**Part 18 incorporates Schedule 2G (1977)**
**Flame-resistant test for conveyor belts in Schedule 2G now designated as Part 18, Section 18.65**
**Continuity maintained on testing and acceptance listing of flame-resistant conveyor belt**

## MSHA Belt Flame Test

**Present conveyor belt flame test is specified in Title 30, Code of Federal Regulations, Part 18, Section 18.65**
**MSHA conducts the flame-resistant test & issues an acceptance for conveyor belts meeting 18.65 requirements**
**Acceptances have been issued to a large variety of conveyor belt constructions**
**Flame-resistant conveyor belt acceptances listed on MSHA A&CC internet page**

## MSHA Belt Flame Test, 18.65

**TEST APPARATUS**
**TEST PROCEDURE**
**TEST CRITERIA FOR FLAME RESISTANCE**
**MSHA ACCEPTANCE AND BELT MARKING REQUIREMENT**

## MSHA 18.65 BELT FLAME TEST

## 18.65 Belt Test Sample

## 18.65 Test Details

**4 belt samples, 6-inches long, 1/2-inch wide by thickness are flame tested**
**3-inch blue flame from a natural gas burner is used to ignite belt sample**
**Burner flame is applied to end of belt sample for 1 minute and retracted**
**An electric fan is turned on to produce an air flow of 300 feet/minute over the belt sample**

## 18.65 Test Details

**The duration of flaming, including glow is timed for each of the 4 tested samples**
**The duration of flaming and any glow for each sample is determined and the results averaged for the 4 samples**
**The criteria for passing the flame test is---**
***Each set of 4 test samples must not result in duration of flame exceeding an average of one minute or afterglow exceeding an average of 3 minutes***

## MSHA Accepted Belts

- 	**Types accepted as meeting 18.65 flame-resistant test----**
**Rubber belts, such as SBR, Butyl & Neoprene****® with 1 to 8 plies**
**PVC, solid woven & coated**
**Composites such as rubber cover and PVC carcass**
**Steel cord belt, such as rubber with various diameter steel cords**
**MSHA acceptance marking assigned for placement on the conveyor belt **** **

## Conveyor Belt Fire Test Program

**Initiated in 1985 by MSHA Technical Support**
**Increase in conveyor belt fires during the 1980’s**
**About 30 % of fires involving conveyor belt traveled hundreds of feet**
**Issue of belt air to evaluate range of air velocities on conveyor belt flammability**

## Fire Test Program Objectives

**Evaluate conveyor belt flammability from low to high air flow**
**Large-scale belt fire tests performed by BuMines in cooperation with MSHA**
**Obtain flammability data on conveyor belts from small-scale tests**
**Utilize data obtained to develop an improved small-scale test for belt flame resistance and approval**

## Large-scale Fire Tests

**Surface fire tunnel constructed at BuMines Lake Lynn Lab near Fairchance, PA**
**The tunnel, about 90 feet long, is connected to an axial vane fan**
**The tunnel is arched with width about 12-1/2 feet and height to center of arch about 8 feet & cross-sectional area of about 81 sq. ft.**

## Large-scale Fire Test Tunnel

## Large-scale Fire Test Tunnel

## Large-scale Fire Tests

**Fire tests conducted on conveyor belts from 30 to 50 feet long and about 40-42 inches wide**
**Belts tested were SBR, Neoprene****®, and PVC meeting the MSHA required 18.65 flame test **
** ****Fire tests made at air flows from about 150 ft./min. to 800 ft./min. **

## Belt setup--Large-scale Tunnel

## Large-scale Belt Fire Test

## Large-scale Belt Fire Testsmoke output

## Large-scale Fire Tests

- 	***Belt fire test results were-*****--**
**Air flow of 300 ft./min. optimum for flame spread**
**Several types of flammability behavior observed—**
**(1) rapid flame spread greater than 13 ft./min. & burning entire belt**
**(2) rapid flame spread charring entire top surface, but bottom of belt undamaged**
**(3) a slowly propagating flame ranging from 1 to about 4-1/2 ft./min. with belt consumed and**
**(4) no flame propagation over the belt length with burning limited to the proximity of the ignition zone   **

## Large-scale Fire Test Data

**More details of the large-scale fire tests and the data obtained are presented in several BuMines and MSHA papers**
**Pass/fail criteria were developed from the large-scale fire tests & the data was used to develop a laboratory-scale belt fire-resistance test**

## Large-scale Test Criteria

- 	**Criteria for pass/fail were developed for the large-scale test as follows—**
**A belt passed if fire damage did not extend to the end of the 30 foot long test sample and—**
**A portion of the test sample was undamaged across its width**
**Of 17 belts tested, 6 passed the criteria**

## Lab-scale Fire Test

**Examples of variables examined in the development were---airflow, test sample width & length, ignition source, & duration of igniting source**
**The lab test chamber developed is 6 feet long by 1-1/2 foot square connected to an exhaust fan transition section**
**A natural gas jet burner is used for the igniting source**

## BELT EVALUATION LAB TEST

## Lab-scale Fire Test

**A steel rack is used to hold the test sample in the tunnel**
**The belt test sample is 9 inches wide by 5 feet long**
**Air flow through the tunnel is set at 200 ft./min.**
**Duration of the natural gas jet burner for ignition is 5 minutes**

## BELT EVALUATION LAB TEST

## BELT EVALUATION LAB TEST

## Lab-scale Belt Fire Test

## Lab-scale Fire Test

**Criteria for pass/fail were developed for the large-scale test as follows—**
**A belt passes if in 3 test trials there remains a portion of the 5 foot sample length that is undamaged across its width**
**A belt fails the test if in any of the 3 test trials fire damage extends to the end of the 5 foot sample length**

## Lab-scale Fire Test

**Comparison of the large-scale test data with the lab-scale test were in good agreement**
**More details of the lab-scale fire tests and the data obtained are presented in several BuMines and MSHA papers**

## Lab-scaleTest Program 

**MSHA public meeting in January 1989 to discuss voluntary test evaluation program with the new lab-scale test and**
**MSHA’s intent to propose rulemaking to replace the 18.65 flame test with the new lab-scale test**

## Lab-scaleTest Program

**21 companies participated in the MSHA voluntary belt test evaluation program**
**Almost 700 individual flammability tests of conveyor belt samples from these companies were made**
**112 different constructions and formulations of belts passed the new lab-scale belt test (designated as BELT)**

## Belt Test Rulemaking

**Rulemaking was initiated in 1989 by MSHA to replace the 18.65 belt flame test with the new lab-scale belt flame test**
**MSHA subsequently proposed a rule for testing & approval of flame-resistant conveyor belts in the Federal Register, Dec. 24,1992**
**Part 75.1108-1 would also be modified to require acquisition of conveyor belts meeting the new test**

## Belt Test Rulemaking

**MSHA held a public hearing on the conveyor belt test rulemaking on May 2, 1995**
**The belt test proposed rule was opened for public comments several times following the proposed rule and public hearing**

## Proposed Rule Withdrawal

**MSHA withdrew the proposed rule for the new conveyor belt test in a Federal Register notice of July 15, 2002.**
**The reasons for withdrawal indicated in the Federal Register notice were---**
**Significant decline in conveyor belt fires (1993-2002)**
**Belt monitoring improvements**
**Technology advancements to minimize friction on the belt such as roller and bearing improvements**