responses ( natural gas Oven)

responses ( natural gas Oven)

asif ali

4/5/2002

Dear Friends

I am very thank ful to all the people who spare some time

and send some informative soloution of my question

We r using Natural Gas base heating Oven

For fabrication of Poly Propylene appliances

we r facing many problem with our appliance (AFO,KAFO,Corset)

like over heat & decomposition of Plastic(Breakage)

Please help me that

Both Poly Propylene & Natural gas (CH4)are organic

Is their combination cause these problems ?

Following is the responses

Bill COPELAND c.p.

I use the same here in the states and have no problems. You may be over
heating polypro should not be over 350 f and try slow ing down the cure
time.

cheryl lewis, orthotic intern

Your problem is not necessarily due to the organic nature of both
substances. It is more likely that the natural gas burners are creating
hot spots in the oven and heating the plastic too fast and unevenly. I
would suggest some sort of barrier between the burning gas and the plastic,
perhaps a thick stone slab - the gas would heat the stone to an even
temperature (it only needs to heat the plastic to around 200C ) and then
the stone would heat the plastic slowly and evenly. If the plastic is on
metal that is directly over the open flame, even if it is a foot or more
away it would heat up too fast and too hot. If you can't use stone then I
would suggest some sort of fan to keep the air circulating quickly around
the oven, this would hopefully reduce the hot spots and uneven heating. How
hot do you set your oven at? Keeping the temperature lower and heating the
plastic up longer creates less stress and degradation of the plastic.

I hope these ideas help - I don't know any of the dimensions or set up of
your oven
so I can't make any direct suggestions but I used to work in a kitchen with
a natural gas oven and I always found the temperature difficult to regulate!


ICRCHOC
Go Electric with a good thermo regulator.

kashinath Sahoo Prosthetist & Orthotist PMT, INDIA

You are correct, it due to the uneven heating.During

heating the gas oven can not distribute heat

uniformly,so there is a localized heat stress which

causes these difficulties.

It is better to use one electrical single/three phase

micro oven with circulating system with temp. and time

control.

L.V.Lebbad RTP

I cant see any safe way to use a gas fired oven ! Some materials used in O

and P have low flash points and can catch fire when introduced to open

flame. BE CAREFUL !

MIR ALTAF HUSSAIN

PLEASE DO NOT USE NATURAL GAS

OVEN IT IS OUT DATED AND VOILATED ACC.TO INTERNATIONAL

LAWS ,AND HAZARD TO THE HEALTH AND MOREOVER THE

PROSTHETICS AND ORTHOTICS QUALITIES CANNOT BE

MAINTAINED THROUGH THIS TYPE OF OVENS.U ARE RIGHT

.SOLUTION i RECOMMENDED ELECTRIC OVEN WHICH HAS

THERMOSTAT CONTROL STARTING FROM 0 degree CENTIGRADE

TO 300 DEGREES .WHICH IS AVAILABLE AT ALL

INTERNATIONAL PROSTHETICS AND ORTHOTICSSUPPLIERS .

WITH REGARDS

Ray D. Smith,CPO,LPO

I previously worked in a lab that used two

restaurant type ovens. If the oven is functioning properly and properly

vented the air in the heat box should have little or no contamination

from the combustion gases. We did have a problem with plastic

degradation that was the result of the technicians leaving the plastic

in the oven longer than required. We also had problems with overheating

the plastic due to a faulty thermostat. We also had problems with

colored plastics not standing up to use due to the dyes interfering with

the molecular structure of the material.

Sajid Saeed,

Here is the solution of your problem,just attach a device that can show you
the temperature of your oven during heating process,and ask your supplier of
polypropylene to provide you the exact degree of heating for different mm
thickness poly. sheets.Because you Know there is different temperature limit
for different Thickness and qualities of sheets,otherwise you can use
Ortholene instead of poly.prop. sheets.

I can provide you the temperature limits of all the sheets provided by
American Plastics Manufacturing companies.If we will not consider the
temperature limits the sheets became brittle,I mean breakable,so ask your
administration to install temperature reading device in you gas oven.



Life