Trying to find a source for cartridge heaters?

[bob8901]

We are wanting to purchase cartridge heaters in small bulk orders of 25-100. I find it odd that every place online still lists a higher price than McMaster. Does anyone here work with these heater enough to know where to get a decent price on them?

We are needing 120V, 100W, diam and length are not set in stone.

 

[moltenmetal]

Watlow are the king of cartridge heaters IMO, but there are a huge number of heater mfgs. Not all of them are equivalent in construction, quality, service life etc.

 

[IRstuff]

Omega sells them as well, but what is a "decent" price?

http://www.omega.com/pptst/CSS_CSH.html

Sometimes, one's expectations are just not realistic.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[bob8901]

Our target pricing is below 10 dollars and most are over 20 so we are somewhat close.

 

[IRstuff]

OK, see:

http://www.aliexpress.com/store/202572/200736505/Cartridge-Heaters.html

No guarantees on quality from me, though...

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[bob8901]

I did find that site but will admit that I would prefer to keep all business in the states. Was really hoping to find a US mfgr but I realize that many companies just import junk and resell here as "US made". I did notice they are gouging a bit on shipping. Pops right on up there for 10 units which should not change shipping price a bit.

 

[IRstuff]

That's not completely true:

http://www.aliexpress.com/store/202...arantee-high-grade-SS-tube-high-temp-MGO.html

only increases $3 going from 1 to 20 units.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[bob8901]

huh, the shipping rate changes depending on the model....

 

[IRstuff]

Well, I'm not them, so it's unclear what the actual costs involved are, but from a unit price perspective, they still seem to meet your cost bogies. Suppliers in China have all sorts of different and obscure shipping structures and prices.

I've gotten stuff that were so unbelievably cheap that they had to have been subsidized, e.g., Bluetooth dongles with price and shipping for $1.50 TOTAL shipped to California. We can't even mail a first-class letter for what it must have cost to ship the dongle across the Pacific.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[bob8901]

I did check pricing with Watlow and found they they will still be a little higher than we expected. I really don't want to lean towards cheap China stuff just yet though. I will continue to shop for some less expensive sources but also at least follow up with this China site to see if they can provide all the engineering data we require.

 

[bob8901]

Our application for these heaters is open air but was told by Omega that virtually all of them will go through thermal runaway if not mated to the proper heat sink. Our whole point here is to simply achieve a surface temp of 1200F for ignition purposes. If we add a heat sink, we will just have to increase the power requirement to heat the larger mass.


Any thoughts on this? can a cartridge heater be tuned to find a happy equilibrium temp without thermal runaway? I know we were going to use a variable control on the heater to adjust it and figured if we got a low enough watt density OR used a 240V heater at 120V, we could get the watt density down to a tolerable level. Basic calcs show we might need about 25watts/sqin or 50 watts total on a heater to achieve our goal. Really not looking forward to complicating the design and add a thermocouple to the system.

 

[IRstuff]

Seems like you're misapplying the products, then. Why not a nichrome wire or heater, if the objective is to cause ignition?

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[Compositepro]

A cartridge heater is not an igniter. Bare nichrome wire will work. Do a Google search for igniters.

 

[bob8901]

Well, we also need something that is robust because it will be subject to some vibration and shock. The cartridge heater is very durable. I have also looked specifically at hot surface ignitors but they are twice the price and are made from a fragile ceramic casting that will break.

Can a cartridge heater not sit and burn red hot in open air without failure? I just don't see much different between this and a tube or Calrod type heater that is common in an oven. That is pretty much what we are after.

I talked with one OEM that indicated our intended purpose and heat selection is already being used successfully in the industry so not sure what to think...

 

[IRstuff]

A cartridge heater is not designed for ignition nor operation while glowing red hot. Very likely, the materials are incompatible with such operation and you'll wind up with a fire hazard.

You MIGHT find one that may work because they designed for it, but you're not going to do so by willy-nilly picking and choosing, particularly if you withhold critical information. We've been talking about your application for two days, and only now you put out information that completely changes the picture. One can only wonder what other critical information you've been hiding.

Nichrome is very robust, and used in hair dryers without any problems.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[Compositepro]

A cartridge heater contains a coil of nichrome wire that is electrically insulated from the case by compressed magnesium oxide powder. This electrical insulator also introduces significant thermal resistance, so the wire is several hundred degrees warmer than the case. That is why cartridge heaters cannot operate at temperatures that come close to the capability of bare wire. This is clearly explained in the literature of any of manufacturer of cartridge heaters.

 

[TXiceman]

You might check Delta Mfg. in Tulsa, OK.

Ken
KE5DFR