ASHRAE Journal - June 2019 - 43

TECHNICAL FEATURE

decade of investigation by SSPC 15 of appropriate speciﬁcations and requirements for the safe application of
this new breed of refrigerants into refrigeration equipment that would be installed in machine rooms. SSPC15
appreciates the many comments that were provided
to the committee on the several APRs and PPRs issued
before ﬁnal publication.
Addendum h modiﬁed portions of Standard 15 to
incorporate speciﬁc requirements for Class 2L refrigerants. Also see Addendum c to Standard 15-2016 for
related changes to Section 8.11.2.1 (the section that
Addendum h renumbers to Section 8.11.5 for the next
edition of the standard). A completely new section,
Section 8.13, addresses machinery room requirements
for refrigeration systems containing 2L refrigerants.
New detailed requirements on refrigerant detectors
are provided in Section 8.13.9, alarm requirements in
Section 8.13.10 and ventilation airﬂow requirements
in 8.13.11. Ventilation airﬂow rates are speciﬁed at two
different levels. The ﬁrst level, referred to as a trouble
alarm, is set to address situation when low leak rates
are sensed (deemed to be levels below the Occupational
Exposure Limit [OEL]). In these cases, a lower ventilation rate (Level 1) is speciﬁed. However, when a larger
leak is sensed (deemed to be refrigerant levels above the
OEL) is addressed by mandating a signiﬁcantly higher
ventilation rate (Level 2).
Because of the differences in refrigerant properties,
discharge pressure relief device section is also updated
to address 2L refrigerants.
Smaller changes of Addenda b, c, e and f. Addendum
b makes several relatively small changes to the standard, including removing a restriction on higher-ﬂammability refrigerants where used in small, portableunit systems. The use of higher-ﬂammability refrigerants is restricted only by the total refrigerant charge in
the self-contained system (limited to 0.331 lb [150 g] of
Group A3 refrigerants). It also deﬁnes "low-probability
pumps" and provides requirements pertaining to their
use. Recognition of low-probability pumps acknowledges the superior leak resistance of these pumps and
encourages their use to increase safety. The approach is
modeled after current allowances for low-probability
systems. Because low-probability systems are inherently more resistant to atmospheric releases than highprobability systems, Standard 15 permits more widespread use of low-probability systems. With respect to

pumps, experience has shown that pump leaks are typically associated with failed seals on rotating (dynamic)
parts, which can result in events ranging from a simple
nuisance release to a hazardous condition requiring an
emergency response. Addendum b encourages the use
of liquid pumps that are hermetically sealed or similar
in lieu of pumps that rely on dynamic seals to contain
refrigerant
Addendum b also eliminates a requirement for industrial occupancies and refrigerated rooms pertaining
to ﬂoor area per occupant. While the requirement has
been in place for some time, upon reexamination by
the committee, there was no logical reason for that section to establish a maximum occupancy limit based on
providing a minimum ﬂoor area per occupant simply
because someone is in a refrigerated area.
Addendum c harmonizes ASHRAE Standard 15 with
Standard 34 to use OEL values as the refrigerant detector
set point for refrigerating machinery rooms to actuate
an alarm and mechanical ventilation. ASHRAE Standard
34-2010 revised the toxicity classiﬁcation deﬁnition to
use "Occupational Exposure Limit" (OEL) in place of
"Threshold Limit Value-Time-Weighted Average" (TLVTWA) and added OEL values to the refrigerant tables,
and Addendum c brought Standard 15 up to speed with
the latest Standard 34.
Addendum e clariﬁed requirements that need to
be met when changing the refrigerant, within the
same refrigerant class per ASHRAE Standard 34. It
lists the restrictions regarding mixing refrigerants
from different refrigerant classes so that the original refrigerant class does not change. For example, a
small amount of A3 refrigerant is added to a product
containing an A1 refrigerant in order to improve oil
circulation at low temperatures. However, the blend
does not change the refrigerant from the original A1
refrigerant class.
Addendum f deleted old Section 8.12(d) and moved
tables from the body of the standard to a normative
appendix, providing an extension of allowable equivalent length of discharge Piping. The tables added more
data for piping nominal diameter (NPS.DN) and Tubing
Diameter O.D. (based on Type L copper).
To close, as always, SSPC 15 encourages comments to
be submitted through the CMP process to help the committee make continual improvements to an already
great, well-known and well-accepted standard.
J U N E 2 0 19

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