Installation guide

-61-
Design & installation Guide For McQuay MDS Multi System
Reinforcement of the air pipe
Generally, the air pipe is reinforced through using the ridge web and ridge lines, or adding
flanges or reinforcing frames. Strictly follow the newest national standard Ventilation and
Air Conditioning Engineering and Acceptance Standard when making and installing the
pipes.
Accessories of the air system
The air system has following accessories: air outlet/return air inlet, outside rainproof
shutter, air flow adjusting valve, smoke discharge & fireproof valve, and air deflector. The
smoke discharge & fireproof valve must be tested before installed. The surface of the air
outlet and the return air inlet must be smooth and even. The size of the neck part must be
within the allowed deviation range so that it can engage with the air pipe tightly. The entire
air conditioning system, including all the accessories, should be firm and tight, and, after
installed, it should be pass the light leakage or air leakage acceptance check for a low-
pressure air pipe system.
Heat insulation of the air system
The heat insulating layer of the air pipe system should also be non-flammable. Generally,
it is 25 mm thick if it is PE materials, or at least 35 mm when consisting of common glass
cotton. This layer should be even, dense, closely attached to the air pipe and its accessories,
and without cold bridges. It should also be well protected against scratch.
Design and calculation of fresh air flow
The fresh air volume mainly depends on the health requirements, the supplementary local air
exhaust volume, and therequirement to guarantee the air conditioned room in positive
pressure
.
Health requirements
Generally, in both the country and the city, the content of carbon dioxide outdoor is 0.5-
0.75g/kg. According to the allowed density of this gas (see the following table), you can use
the overall ventilation volume defined in the Industrial Ventilation to calculate the volume
of fresh air needed to eliminate it.
Elbow
The rectangular air pipe can be inner-arc or inner-slanting, as shown in Figure. When the
longest side A is 500 mm or longer, a flow deflector must be used.
Wall thickness of the air pipe
The wall thickness directly relates to the effect and life of the pipe.Too thin wall will cause
unstable installation, and thus the pipe will heavily with noise increased. Even worse, the friction
might compound the problem, shortening the service life of the air pipe or even the entire air
conditioning system.
Air pipe elbow
(a) inner and outer-arc elbow (b) inner-arc elbow (c) Inner-slanting elbow
320 340 450 480 630 670 1000 1120 1250 1320 2000
Low-speed air pipe 0.5 0.6 0.8 1.0 1.2
High-speed air pipe 0.8 0.8 0.8 1.0 1.2
Round air pipe 0.5 0.6 0.8 1.0 1.2
Connection mode Insertion Flange
Unit: mmRecommended thickness of steel air pipes and accessories
Diameter of round air pipe or
length of the longest side of rect-
angular air pipe
Rectangular
air pipe