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Heating Systems
Published in Fred Hall, Roger Greeno, Building Services Handbook, 2017
Current practice is to use jointless plastic piping in continuous coils. Pipes can be embedded in a 70 mm cement and sand screed (50 mm minimum cover to tube). In suspended timber floors the pipe may be elevated by clipping tracks or brackets with metallic reflective support trays, prior to fixing the chipboard decking. Materials include: PEX: Cross-linked polyethylene.PP: Co-polymer of polypropylene.PB: Polybutylene.
Plastics
Published in Arthur Lyons, Materials for Architects and Builders, 2019
Cross-linked polyethylene (PEX), manufactured by the action of peroxide catalyst on normal polyethylene, is used for domestic hot water and underfloor heating systems as it can withstand operating temperatures up to 90°C. In underfloor heating systems, an interlayer of aluminium is incorporated into the PEX pipe to prevent the ingress of oxygen, which would cause corrosion of steel components within the system. Certain barrier composite pipes can operate at temperatures up to 95°C.
HEATING SYSTEMS
Published in Fred Hall, Roger Greeno, Building Services Handbook, 2011
minimum cover to tube). In suspended timber floors the pipe may be elevated by clipping tracks or brackets with metallic reflective support trays, prior to fixing the chipboard decking. Materials include: PEX: Cross linked polyethylene. PP: Co-polymer of polypropylene. PB: Polybutylene. These pipes are oxygen permeable, therefore, when specified for
Medical textiles
Published in Textile Progress, 2020
Cross-Linked Polyethylene (PEX, XPE or XLPE) is high-density polyethylene within which covalent bonds have been formed either by chemical modification through attachment of silanes, by heating in the presence of peroxide crosslinking agents or by irradiation with an electron beam to interconnect its polymer chains to form 3-dimensional polymers with high molecular weights and improved physical properties. The molecular structure that is formed by crosslinking provides greater resistance to stress cracking, improved toughness, stiffness, and chemical resistance compared to the HDPE used as the precursor, but the likelihood of such improvements may be improved by increasing crystallinity in the precursor prior to its crosslinking. Improvements in both tensile strength (50% increase) and Young’s Modulus (36% increase) were reported in UHMWPE fibres by virtue of cross-linking compaction at elevated temperatures in the presence of peroxide [166]. It is certainly a high-performance fibre but there are concerns that highly-cross-linked polyethylene (HXLPE), made by forming cross linkages in UHMWPE may be too unforgiving to the host in some medical applications, although these observations related to liners made from HXLPE rather than the filament forms [148].
Above-floor tube-and-plate radiant floor model development and validation
Published in Journal of Building Performance Simulation, 2018
S.A. Brideau, I. Beausoleil-Morrison, M. Kummert
The tubes were made of cross-linked polyethylene (PEX). The thermal conductivity of PEX was taken to be 0.38 W m−1 K−1, while the density and specific heat were taken to be 938 kg m−3 and 550 J kg−1 K−1 respectively. The tube inner and outer diameters were taken to be 0.0127 and 0.016 m, respectively. Table 1 summarizes the construction of the floor.