Question regarding pex heat transfer

[eeprom]

Hello,
I'm trying to do some conductive heat transfer calculations for two types of pex pipe, "normal" pex and insulated pex. All I need is the heat transfer coefficients (units: BTU/(hr ft^2 F). I've done enough google searches to know I must be looking in the wrong place. Can someone direct me to where I can find spec sheets on various types of Pex. In addition to the heat transfer coefficient, I'd also need the OD.

thanks
EEPROM

 

[IRstuff]

Why would anyone here know what your OD is? Or what type of insulation you're planning on using?

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[zekeman]

For such a vague question, let me start by referring you to

http://www.pexflex.net/html/docs/PEXFLEX_Datasheet.pdf

After you read it, ask us more questions. I think you want overall heat transfer coefficients for various pipe sizes w and without insulation.

Also it would help if you stated the application.

 

[ione]

Eeprom,

You had an exceedingly stern reaction, especially considering you’re asking for advices for free. If you only had glanced to IRstuff’s profile on eng-tip community, you’d have seen he’s a very active member, who has offered and keeps offering many useful advices. In this case he’s just outlined how improper was your enquiry.

 

[ione]

Ah, that’s what you were looking for.

ASTM F876 – Standard Specification for Crosslinked Polyethylene (PEX) Tubing.

ASTM F877 – Standard Specification for Crosslinked Polyethylene (PEX) Plastic Hot- and Cold-Water Distribution Systems.

ASTM F2080 – Standard Specification for Cold-Expansion Fittings With Metal Compression-Sleeves for Cross-Linked Polyethylene (PEX) Pipe.

CSA B137.5 – Crosslinked Polyethylene (PEX) Tubing Systems for Pressure Applications.

DIN 4726 – Plastic Piping Used in Warm Water Floor Heating (Warmwasser-Fußbodenheizungen und Heizkörperanbindungen - Rohrleitungen aus Kunststoffen).

 

[moltenmetal]

All you need is the heat transfer coefficients, which are of course ENTIRELY dependent on the application. Is this PEX tubing embedded in concrete? Hanging in free air? Inside a wall cavity? Coaxial inside another piece of pipe? Outdoors or indoors? Is it PEX, or PEX-Al-PEX composite tubing? What's the operating temperature? What sort of insulation? What OD of pipe/tube and insulation? What thickness of each?

You're looking for more than datasheets, I'm afraid.

 

[ione]

Maybe he meant thermal conductivity (Btu/hr/ft/F), which in the end is almost the same thing as heat transfer coeffcient (Btu/hr/ft^2/F) for someone who makes calculations and take decisions

 

[eeprom]

Ione,
Thank you. That is what I was looking for. I appreciate the help.

EE