Technical note · Healthcare mechanical services
Medical gas plant and reticulation design for South African hospitals
Who does this work, what the regulation actually
prescribes, and why an outlet count is not a plant size. Three documents divide
the job between them, and only one of the three is binding by law in the
province the project sits in.
A consulting engineer designs medical gas plant and reticulation; a
specialist installer builds it. Lombard Consulting Engineers does that
design work for hospitals in the Western Cape and Gauteng: the diversified flow
calculation, plant and pipe sizing, and the specification. The Western Cape
regulation pipes oxygen, nitrous oxide, medical air, vacuum and
scavenging to every theatre.
The design is the consulting engineer’s deliverable, and it is finished before tender
On a hospital project the medical gas pipeline system is designed
by the consulting engineer and built by a specialist installer. The engineer
establishes which services reach which clinical area, calculates the diversified
flow for every gas, sizes the source plant and the pipework, and writes the
specification. That package is complete before the work goes out to tender,
because it is what the tender is priced against.
Lombard Consulting Engineers does the design and the specification, and
inspects the installation. LCE does not install medical gas systems and does not
supply medical gas equipment. The distinction matters at appointment: an
installer prices and builds what a design describes, and somebody has to have
written the design and be answerable for it against the regulation.
In the Western Cape the regulation makes that explicit, and it does not stop at
handover. Requirement 4 of Annexure B obliges the proprietor of a private health
establishment to obtain certification every twelve calendar months from an
appropriately qualified engineer that requirements 6 to 22 have been met
— and the medical gas requirements are requirements 15 to 20, inside that
range. A hospital’s gas installation therefore needs an engineer annually, not
only at construction.
Requirement 4 of Annexure B to Provincial Notice 187 of 2001. The
certification must be furnished to an inspecting officer on request. The gases
requirements are 15 to 20 of the same Annexure.
Three documents do different jobs, and only one of them applies by law
A private hospital in the Western Cape is governed by the
Private Health Establishment Regulations, Provincial Notice 187 of 2001,
whose Annexure B sets the minimum installation requirements. It prescribes which
services are piped where, the pipeline pressures, alarms and back-up, and the
theatre outlet counts. It prescribes no flow rate and no plant size.
Those come from HTM 02-01, a UK design standard used as the reference
method for calculating flow and sizing the source. The installation itself
— materials, terminal units, testing and colour coding — is addressed
by SANS 7396-1. Only the first of the three is binding by law; the other
two bind where a regulation, a client standard or the contract calls them up.
This is the single most important thing to get right about the South African
regulatory position, and it is routinely got wrong: licensing of private health
establishments is administered provincially, so the instrument that applies
depends on the province the project is in. P.N. 187 of 2001 was made by the
Western Cape Minister of Health under section 44 of the Health Act 63 of 1977,
and it applies to private health establishments in that province.
| Document | Status | What it sets on this page |
|---|---|---|
| Private Health Establishment Regulations (P.N. 187 of 2001) | Western Cape provincial regulation — binding on private health establishments in that province | Which gases are piped to which area; theatre outlet counts; pipeline pressures; alarms; back-up; emergency power |
| SANS 7396-1:2009 | South African standard for medical gas pipeline systems — a modified adoption of ISO 7396-1:2007 | The pipeline installation itself: materials, terminal units, testing and colour coding, with three South African national modifications |
| HTM 02-01 Part A | UK health technical memorandum — a design reference, not law in South Africa | The diversified flow method that sizes the source, the continuity-of-supply requirement, and the pipe pressure-loss method |
P.N. 187 of 2001, published in the Province of Western Cape
Provincial Gazette Extraordinary 5728 on 22 June 2001 and in operation from
1 July 2001; regulation 2(1) for application, regulation 23 for Annexure B.
SANS 7396-1:2009 Edition 1, published December 2009. HTM 02-01 Part A, published
1 May 2006 and still the current edition. Confirm which provincial instrument
applies to your project — see the scope note.
SANS 7396-1 is the South African standard for the pipeline itself
SANS 7396-1:2009 covers medical gas pipeline systems for
compressed medical gases and vacuum. It is a modified adoption of
ISO 7396-1:2007, published in December 2009 and approved by SABS technical
committee TC 58. Where the regulation says which gases reach which room and
HTM 02-01 supplies the sizing method, SANS 7396-1 is the document that addresses
the installation itself — materials, terminal units, testing and colour
coding.
The national modifications are the part worth knowing, because they are where a
design drawn from the ISO text alone goes wrong. SANS 7396-1 substitutes South
African standards for two of the European ones ISO cites: terminal units are
defined by SANS 1409 rather than ISO 9170-1, and copper tube for medical
gas and vacuum is covered by SANS 1453 rather than EN 13348. Gas colour coding
is nationally modified as well.
That substitution is not academic. Requirement 3 of Annexure B to Provincial
Notice 187 of 2001 already required the construction of a private health
establishment to comply with SABS 1409, outlet sockets for medical gas,
alongside SABS 051 Part 3 on the handling and storage of medical gas and
SABS 0224 on non-flammable medical gas pipeline. The regulation and the standard
point at the same South African terminal-unit document, from opposite directions
and eight years apart.
SANS 7396-1:2009 Edition 1, national foreword: approved by SABS
TC 58, published December 2009, a modified adoption of ISO 7396-1:2007, with
national modifications at clause 2 and subclause 10.2. Its technical content is
not reproduced here.
Called-up standards from requirement 3 of Annexure B to Provincial
Notice 187 of 2001, quoted in the regulation’s own designations — these are
pre-2003 SABS numbers and several have since been renumbered into the SANS series,
so confirm the current equivalent of each. SANS 7396-1 is a standard rather than a
regulation: it binds where a regulation, a client standard or the contract calls
it up.
What the regulation prescribes for a theatre is an outlet count, per room
Annexure B requirement 66 gives each theatre category a
prescribed number of installations, and a major theatre gets 2 oxygen points,
1 nitrous oxide, 2 vacuum, 1 medical air and 1 scavenging point, plus 8
electrical points. Requirement 15(1) separately requires that oxygen, nitrous
oxide, medical air, vacuum and scavenging all be piped to an operating theatre
unit, so all five services are mandatory even where the count is one.
| Theatre type | Oxygen | Nitrous oxide | Vacuum | Medical air | Electrical | Scavenging |
|---|---|---|---|---|---|---|
| Minor | 2 | 1 | 2 | 0 | 6 | 1 |
| Major | 2 | 1 | 2 | 1 | 8 | 1 |
| Cardiac | 3 | 2 | 3 | 2 | 10 | 1 |
| Cardiac catheterisation lab | 1 | 1 | 1 | 0 | 8 | 1 |
Table A, requirement 66 of Annexure B to P.N. 187 of 2001,
reproduced in full. Requirement 67 adds one oxygen point, one vacuum point and a
neonatal resuscitation area or mobile resuscitation unit to any theatre unit
where Caesarean sections are performed. Requirement 65 sets the minimum theatre
dimensions the counts sit inside: a minor theatre 20 m², a major theatre
30 m², a cardiac theatre 45 m² and a catheterisation laboratory
42 m², all at 3 m ceiling height.
Table A is a count per room, and it does not say how those points are
distributed between the service positions in the room. A modern theatre has an
anaesthetic position, a surgical position and a wall panel, and the regulation is
silent on how the prescribed points are shared between them.
It is also a floor rather than a design. The ventilation of the same room is
set by different documents again — SANS 10400-O:2025 and the gazetted IUSS
norms — and that calculation is covered in
the note on operating theatre
ventilation design.
The regulation fixes the pipeline pressures, and they are not the same number
Annexure B requirement 19 sets two distinct pressures. Medical
air for respiratory purposes is supplied at a fixed pipeline pressure of
400 kPa. Medical air for driving surgical power tools is supplied at a
terminal usage pressure between 700 kPa and 1 000 kPa, depending on the
tools and equipment to be used. The same requirement obliges intensive care
units and operating theatre units to be provided with a back-up system.
That is why medical air and surgical air are two systems rather than one
system with a regulator on the end of it, and why a bill of quantities that
lists a single “medical air” installation has already lost a distinction the
regulation makes.
| Requirement | What it prescribes | Reference |
|---|---|---|
| Medical air, low pressure, respiratory | Fixed pipeline pressure of 400 kPa | req 19 |
| Medical air, high pressure, surgical tools | Terminal usage pressure 700 kPa to 1 000 kPa, by the tools used | req 19 |
| Back-up on critical systems | Intensive care units and operating theatre units must be provided with a back-up system | req 19 |
| Mobile back-up | All piped vacuum and oxygen systems must have mobile back-up systems, with staff trained to use them | req 18 |
| Gas alarms | Alarm monitoring all gases except scavenging, in every 24-hour nurse station in the theatre complex, with a slave panel in the ICU or another easily visible position, on the emergency power supply | req 17 |
| Emergency power | The emergency generator must supply the medical air compressors, vacuum pumps and gas alarm systems | req 11(6) |
| Scavenging balancing | Each scavenging outlet point must have its own balancing valve, so the system can be balanced progressively from the furthest outlet towards the fan motor | req 20 |
Annexure B to P.N. 187 of 2001, requirements 11(6), 17, 18, 19
and 20. Requirement 15 additionally requires piped medical gases and vacuum in
all units where patients are accommodated or treated, other than sub-acute and
hospice facilities, with mobile gas services available for crisis situations.
An outlet count is not a plant size, and the gap is about six times
The regulation prescribes terminal units. It prescribes no flow
rate at all — searched, and there is no litres-per-minute figure, no
diversity method and no source-sizing requirement anywhere in it. So a design
that satisfies the outlet counts and stops there has no calculated flow behind
it, and therefore no defensible plant size. The flow calculation is what turns a
count of outlets into a source capacity.
Table A, major theatre 2 oxygen points × 4 theatres = 8 terminal units
HTM 02-01 cl 4.18, each must pass 100 L/min 8 × 100 = 800 l/min connected
HTM 02-01 cl 4.18, diversified 100 + (4 − 1) × 10 = 130 l/min
As a volume flow 130 l/min = 7,8 Nm³/h
The connected load is 6,2 times the design flow. Size
the source on the outlet count and it is roughly six times too large; size it
on the outlet count with no flow calculation at all and there is no figure to
defend. The 100 L/min sets what each terminal unit must be able to
pass, which is a different question from what the source must
deliver, and conflating the two is the most common costly error at concept
stage.
Statutory count from Table A, requirement 66 of Annexure B to
P.N. 187 of 2001. Flow basis: HTM 02-01 Part A clause 4.18, which requires each
oxygen terminal unit in an operating room and anaesthetic room to be able to
pass 100 L/min, and gives the diversified flow as 100 L/min for the first
operating room and 10 L/min for the remainder. Computed with LCE’s gated design
engine. One arrangement, as an illustration — change the theatre count or
the categories and the answer moves.
Two flows are worth knowing beyond the theatre suite, because both are
regularly missing from a brief. Anaesthetic room induction flow is not
added to the theatre flow, on the reasoning that a patient is unlikely to be
induced while a patient in the associated theatre is still under anaesthetic.
And CPAP ventilation carries a diversified flow of 75 L/min for 75 % of
beds, which is 56,25 l/min per designated bed — usually the largest
single influence on oxygen source sizing, and the figure most often left out.
HTM 02-01 Part A clauses 4.19 and 4.23. Clause 4.23 also warns
that incorrectly set ventilators can use in excess of 120 L/min, and that raised
ambient oxygen concentration is itself a ventilation design problem where many
CPAP machines run in one room.
Every system except vacuum needs a third means of supply
HTM 02-01 clause 2.25 requires continuity of supply to be
achieved four ways together: duplicate components, a third means of supply
for all systems except vacuum, alarm systems, and connection to the
emergency power supply system. Liquid oxygen systems are the stated exception on
duplication, because a liquid system may instead include a secondary vessel.
The South African regulation reaches the same place by a different route.
Requirement 18 of Annexure B requires mobile back-up on all piped vacuum and
oxygen systems; requirement 19 requires a back-up system for intensive care and
theatre units; and requirement 11(6) puts the compressors, vacuum pumps and gas
alarms on the emergency generator. Two documents, written twenty-five years and
one hemisphere apart, agreeing that a single source is not a supply.
Pipework is sized on pressure loss, and the fittings allowance moves the answer
Medical gas pipework is sized on pressure drop rather than on
velocity, using the pressure-loss method in Appendix G of HTM 02-01, and
selection is by distribution pressure rather than by gas — the
400 kPa tables carry oxygen, nitrous oxide, Entonox and medical air alike. The
permitted drop is the engineer’s decision, taken per system and recorded,
because it is the number that decides whether a bore is adequate.
The straight-pipe result is not the answer, though. Appendix G notes that in
practice many designers add 25 % to 30 % to the total measured length, or
use only 60 % to 75 % of the allocated pressure drop, to account for the
frictional resistance of valves and fittings. On a real run that allowance is
frequently the difference between one pipe size and the next.
Straight pipe, 60 m 12 mm OD → 12,04 kPa passes
Add 30 % for fittings 60 m → 78 m equivalent
Straight-pipe answer re-checked 12 mm OD over 78 m → 15,97 kPa fails
Next size up 15 mm OD over 78 m → 5,17 kPa passes
The fittings allowance alone moves the answer one pipe
size. A 12 mm bore sized on the measured length does not meet the 14 kPa
it was chosen for once the fittings are counted; it overshoots by 14 %. The
step to 15 mm then lands at a third of the allowance, which is the other half
of the point — pressure loss goes as the square of flow, so pipe sizing
on this method is coarse, and the useful engineering decision is the allowed
drop, not the arithmetic.
Method: HTM 02-01 Part A Appendix G, equation 2, applied as
dp = (L / Ltable) × (Q / Qtable)² ×
dptable, with Appendix G paragraph 13 for the 25 % to 30 % length
allowance. Copper outside diameters, computed with LCE’s gated design engine; the
underlying tables are not reproduced here.
The 14 kPa is not an arbitrary budget — the Appendix G table
for 400 kPa pipelines is set out against three pressure-loss classes, 7, 14 and
21 kPa, and 14 kPa is the middle one.
Common questions
Who designs medical gas plant and reticulation for hospitals in South Africa?
The consulting engineer. The diversified flow calculation, the source plant
sizing, the pipe sizing, the drawings and the specification are the engineer’s
deliverable, and they are complete before the installation goes to tender. A
specialist installer then prices and builds to that design. Lombard Consulting
Engineers does this design work for private and public hospitals in the Western
Cape and Gauteng, and does not install or supply medical gas equipment.
What regulations govern medical gas installations in South African hospitals?
Licensing of private health establishments is administered provincially, so
the instrument depends on the province. In the Western Cape it is the Private
Health Establishment Regulations, Provincial Notice 187 of 2001, whose
Annexure B prescribes which gases are piped to which clinical area, the theatre
outlet counts, the pipeline pressures, alarms and back-up. It prescribes no flow
rate, so the flow calculation and plant sizing are taken from a design standard
— in LCE’s work, HTM 02-01 Part A.
Does SANS 7396 apply to medical gas installations in South Africa?
SANS 7396-1:2009 is the South African standard for medical gas pipeline systems
for compressed medical gases and vacuum, and it is a modified adoption of
ISO 7396-1:2007 published in December 2009. It is a standard rather than a
regulation, so it binds where a regulation, a client standard or the contract
calls it up. Its national modifications point at South African documents for two
things the ISO text handles differently: terminal units are defined by SANS 1409,
and copper tube for medical gas and vacuum by SANS 1453.
How often must a hospital medical gas installation be certified?
In the Western Cape, every twelve calendar months. Requirement 4 of Annexure B
to Provincial Notice 187 of 2001 obliges the proprietor of a private health
establishment to obtain certification from an appropriately qualified engineer
that requirements 6 to 22 have been met, and the medical gas requirements are 15
to 20, inside that range. The certification must be furnished to an inspecting
officer on request.
How many oxygen outlets does an operating theatre need?
Under Table A of Annexure B to Provincial Notice 187 of 2001, a major theatre
is prescribed 2 oxygen points, a cardiac theatre 3, a minor theatre 2 and a
cardiac catheterisation laboratory 1. Those are minima per room, and the
regulation does not say how they are shared between the anaesthetic position,
the surgical position and the wall panel. A theatre unit where Caesarean
sections are performed gets one additional oxygen point and one additional
vacuum point.
What pressure is medical air piped at in a South African hospital?
Two pressures, because there are two systems. Requirement 19 of Annexure B to
Provincial Notice 187 of 2001 sets medical air for respiratory purposes at a
fixed pipeline pressure of 400 kPa, and medical air for driving surgical power
tools at a terminal usage pressure between 700 kPa and 1 000 kPa depending on
the tools. The same requirement obliges intensive care units and operating
theatre units to have a back-up system.
How is medical gas plant sized?
On diversified flow, not on outlet count. The outlet count sets what each
terminal unit must be able to pass; the diversified flow sets what the source
must deliver, and the two differ by a large factor. For oxygen to operating
rooms, HTM 02-01 clause 4.18 gives 100 L/min for the first operating room and
10 L/min for the remainder, so a four-theatre suite designs at 130 l/min while
its eight terminal units could pass 800 l/min between them.
Does a hospital need three medical gas sources?
On every system except vacuum, yes. HTM 02-01 clause 2.25 requires duplicate
components, a third means of supply for all systems except vacuum, alarm
systems, and connection to the emergency power supply. Liquid oxygen systems may
instead include a secondary vessel. In the Western Cape, Annexure B to
Provincial Notice 187 of 2001 separately requires mobile back-up on all piped
oxygen and vacuum systems, and a back-up system for intensive care and theatre
units.
How is medical gas pipework sized?
On pressure loss, using Appendix G of HTM 02-01, and selected by distribution
pressure rather than by gas — one set of tables serves oxygen, nitrous
oxide, Entonox and medical air at 400 kPa. The permitted pressure drop is the
engineer’s decision, recorded per system. Straight-pipe loss is not the answer
on its own: Appendix G notes that many designers add 25 % to 30 % to the
measured length, or use only 60 % to 75 % of the allocated drop, for valves and
fittings.
What services must be piped to an intensive care unit?
Medical air, oxygen and vacuum, under requirement 15(2) of Annexure B to
Provincial Notice 187 of 2001. The outlet provision is set separately at
requirement 55(6): three oxygen outlets, three low-pressure medical air outlets
and three vacuum outlets for every two beds, at the head of the bed. A recovery
area is treated differently again, at requirement 70(2) — one oxygen, one
vacuum and low-pressure medical air for each bed accommodated.
What is anaesthetic gas scavenging, and what flow is it designed for?
It is the low-pressure suction system that removes exhaled anaesthetic gases
from the patient circuit, and requirement 20 of Annexure B to Provincial Notice
187 of 2001 makes it mandatory in a theatre unit, with a balancing valve on
every outlet point so the system can be balanced from the furthest outlet
towards the fan motor. The disposal flow is a project decision: HTM 02-01 clause
10.16 gives a maximum of 130 L/min under BS 6834:1987 and 80 L/min under
ISO DIS 7396-2:2005.
Is medical gas design different from theatre ventilation design?
Different systems, different governing documents, one design team. Medical gas
is set by Provincial Notice 187 of 2001 and HTM 02-01; theatre air volumes,
pressure cascade and airflow pattern are set by SANS 10400-O:2025 and the
gazetted IUSS health facility norms, which is a separate calculation covered in
the note on operating theatre
ventilation design. They meet in the same room and on the same drawing,
which is why they are usually one appointment.
Which regulation applies to your project. Provincial Notice 187 of
2001 is a Western Cape instrument: it was made by the Western Cape
Minister of Health under section 44 of the Health Act 63 of 1977, and
regulation 2(1) applies it to private health establishments in that province.
Licensing of private health establishments in South Africa is administered
provincially. So on a project outside the Western Cape the applicable instrument
must be confirmed before any prescribed count on this page is relied on. This
note does not state what applies in the other provinces.
Scope of this note. It covers who does the design, what the Western
Cape regulation prescribes, the diversified flow principle, continuity of
supply and the pipe pressure-loss method. It does not cover terminal
unit provision above the statutory minimum, source plant configuration and
selection, liquid oxygen vessel sizing, manifold and cylinder banks, testing,
commissioning and validation, or laboratory gas and LPG reticulation. Those
are project work, not published figures.
Editions and sources. Provincial Notice 187 of 2001 is quoted from
the Province of Western Cape Provincial Gazette Extraordinary 5728 of 22 June
2001, in operation from 1 July 2001. HTM 02-01 Part A was published on 1 May
2006 and is still the current edition.
HTM 02-01 is UK Crown copyright. It is cited here as a small number of
individual values and requirements, each attributed to its clause, and no
table from it is reproduced. Where one of its figures is a per-project
choice rather than a fixed value — the scavenging disposal flow is the
clearest case, at 130 or 80 L/min depending on the standard applied —
this note says so rather than picking one.
SANS 7396-1:2009 is SABS copyright and licensed to a single holder. It is
named, dated and described here, and none of its technical content is
reproduced. The same applies to SANS 1409 and SANS 1453, which are named
because the standard and the regulation both point at them.
Every quantity on this page is a regulatory minimum or a design method, not
a setpoint, and none of them is a substitute for a project-specific design.
This note describes what the documents require of work still at concept stage.
It makes no assessment of any particular installation.
Medical gas design enquiries
Lombard Consulting Engineers designs medical gas plant and reticulation for
private and public hospitals in the Western Cape and Gauteng, alongside
laboratory gas and LPG reticulation and the wider hospital mechanical and
electrical services. Call
+27 (0)87 805 9452 or email
office@lceng.co.za.
Related technical note:
Operating theatre ventilation
design in South Africa — SANS 10400-O:2025 outdoor air rates, the
gazetted IUSS pressure cascade, and unidirectional airflow requirements.