3.1.3.4
Piping, Valves, and Accessories
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NOTE: In most instances, freezing temperatures at
the project location dictate the use of an
uninhibited propylene-glycol/water solution.
USP/food-grade uninhibited propylene-glycol is a
nontoxic, noncorrosive fluid used by the food
industry, and has been approved for use with single
isolation heat exchangers in closed-loop military
solar energy systems by the Office of the Surgeon
General (DASG) in coordination with the Toxicology
Division of the Army Environmental Hygiene Agency.
The concentration to be used is a function of the
climate where the system is to be located. The
concentration should be either 30 or 50 percent,
with climates that commonly attain freezing
temperatures (those above approximately 2,222
heating Kelvin days (4000 heating degree F days))
receiving the 50 percent solution. Although
inhibited propylene-glycol is often used in
mechanical systems, uninhibited propylene-glycol is
specified for solar systems to eliminate fluid
maintenance requirements. Indicate in equipment
schedules on drawings the heat transfer fluid used,
the concentration, and the maximum operating
temperature to assure proper equipment and materials
compatibility. Water should only be used as a heat
transfer fluid when the direct circulation system is
specified. Items to be shown on the drawings
regarding the heat transfer fluid must include, if
applicable:
a. Use of uninhibited, food-grade propylene- glycol
and distilled water solution
b. 30 or 50 percent concentration
c. Note of tamper resistant seal requirement.
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Piping shall be installed in accordance with Section 15400A PLUMBING,
GENERAL PURPOSE, except where noted otherwise. Solders used on piping
shall be as shown. Piping shall be coded with fluid type and flow
direction labels in accordance with Section 09900 PAINTS AND COATINGS.
When a food-grade uninhibited propylene-glycol solution is used to heat
potable service water, tamper resistant seals must be attached to all fill
ports. All propylene-glycol circuits must be labeled "CONTAINS UNINHIBITED
FOOD-GRADE PROPYLENE-GLYCOL: INTRODUCTION OF ANY NONAPPROVED FLUID MAY
CONSTITUTE A HEALTH HAZARD." All tamper resistant seals must carry the
name of the registered engineer or licensed plumber who certifies that only
a [30] [50] percent food-grade uninhibited propylene-glycol and water
solution has been installed in the system. Air vents shall be installed at
the high points of the collector array and in the equipment room.
3.1.3.5
Pipe Expansion
Expansion of supply and return pipes shall be provided for by changes in
the direction of the run of pipe or by expansion loops as indicated.
Expansion loops shall provide adequate expansion of the main straight runs
of the system within the stress limits specified in ASME B31.1. Loops
SECTION 13600A
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