M2
Fastener Data 1Fastener Data 2
Mechanical / HVAC
It is important to note that in some
cases codes or design criteria may
Air Flow out of grilles and diffusers
not allow this liberty. In other
should be rounded to even increments of
cases however, 2 or 3 % analysis may
5 or 10 L/s, wherever possible.
be feasible, and could lead to
rounded, easily spoken numbers.
Ductwork (Round, Rigid) Most designers
are showing hard metric diameters. (ex,
Temperature People will rarely
250, 300)
speak in decimal degrees. (ex, 23.8
degrees C). All mechanical schedule
Ductwork (Round, Flexible) Many
temperatures, design temperatures,
designers are showing flexible round
leaving and entering temperatures,
duct in hard metric sizes, but
and others shall be stated in even
accepting soft metric during
Celcius (ex, 5, 12, 25, and 40
construction. (ex, 200, 250)
degrees C) unless not possible.
Ductwork (Rectangular) Use 50 and 100
New construction projects shall use
mm sizes,
Celcius only.
(ex, 500 x 1000, 250 x 350) unless not
possible.
Renovation projects where new
control systems are being installed,
Equipment We regularly receive updated
should use Celcius.
catalogs from producers that have added
metric data to their catalogs or
HVAC calculations shall be in SI to
literature. Where this did not exist,
the fullest extent possible.
we have had no difficulty receiving
modified data on a project, or
Thermal Ratings for boilers and
obtaining a bond paper supplement.
chillers should be specified in even
nominal MW or kW increments to the
Schedules To think metric, flow rates,
largest degree possible:
pressures, thermal powers, and other
(Ex, 500 kW, 0.9 MW, 3.5 MW)
criteria on schedules should be rounded
wherever possible.
Pipe Steel pipe (ASTM A53) and
copper tube sizes (ASTM B88) will
The 1 % Analysis provides a useful
not physically change by switching
technique.
to the metric system. They are now
classified by new nominal mm sizes.
Ex 1, A fan flowrate converts to 8,022
L/s.
ASTM B88M, hard metric copper tube
1% is +/- 80.22 L/s. This fan could
sizes, should not yet be utilized.
possibly be shown as minimum 8000 L/s
(8 m3/s) and is easier and faster to
Schedule designations remain the
say.
same (example: Schedule 40, and type
K,L,M)
Ex 2, A pump flow converts to 75.7 L/s.
1 % of this is 0.757 L/s. 75 L/s could
The Mechanical Task Group, under
possibly be used.
leadership of ASME, recently
27
Previous Page
