request for advice/ help from any SSD and HVAC engineering gurus

[Lindy Ryan]

Hello SSD and HVAC engineering gurus

My question is

the current configuration of one of our facilities new clinic services buildings (about to be commissioned) is that all sterile stock rooms (4 Rooms) are off the same AHU and therefore have no redundancy if the unit was to fail the would compromise all 4 rooms. The other problem with this design is that when the door is opened to the main sterile stock room it affects the other 3 rooms dropping the differential pressure across the doors below 7pa and if those door are open at the same time there would be minimal pressure with the potential for contaminated air flowing into these sterile stock rooms.

I can find in the engineering services guidelines that sterile store to corridor should be to 10pa and each pressure gradient step should be designed to 10pa however there is no clarity around:

* Should all four rooms be off the same AHU
* What is the minimal accepted pressure drop whilst a door is open or is the system to maintain 10pa across the door if open
* If there is a minimum pressure drop level, how long can this occur for before the sterile room is compromised

Can anyone advise/ help me with more useful advice as this is what we will be left with but I have my concerns and our builders are asking for evidence that what they have set up meets specs..I have concerns …am I wrong?

Any feedback gratefully acknowledged as we have little time to respond and lodge a response

Kind regards

Lindy

Lindy Ryan

District Infection Prevention & Control CNC | Clinical Governance & Information Services MNCLHD
Level 1 Coffs Specialist Centre, Pacific Hwy, Coffs Harbour
Office 66911984 or Mob 0419 990 693 | lindy.ryan@health.nsw.gov.au
http://www.health.nsw.gov.au

General email enquires please use this email MNCLHD-InfectionControl@health.nsw.gov.au

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“Wise and humane management of the patient is the best safeguard against infection”
(Florence Nightingale Circa 1860)

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[Robyn Lawson]

Hi Linda

Not sure if you have received any response to your questions regarding ventilation in the sterile store rooms.

Your situation does not appear right as other rooms air supply should not be compromised.

In Western Australia we use the Western Australian Health facility guidelines for Engineering Services. Available on the WA DOH website.

Sterile store rooms –
-4.6- supply air shall be HEPA filtered
– Rooms shall be at positive pressure relative to surroundings. A minimum ventilation rate of 10 air changes per hour shall be provided.

Also 14.6.2 tells you further information about supply air and compliance with AS/NZS 1668.2 .

Best of luck

Robyn Lawson
OR Consulting Australia
roblily49@gmail.com
0408 871 624

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Hello SSD and HVAC engineering gurus

My question is

the current configuration of one of our facilities new clinic services buildings (about to be commissioned) is that all sterile stock rooms (4 Rooms) are off the same AHU and therefore have no redundancy if the unit was to fail the would compromise all 4 rooms. The other problem with this design is that when the door is opened to the main sterile stock room it affects the other 3 rooms dropping the differential pressure across the doors below 7pa and if those door are open at the same time there would be minimal pressure with the potential for contaminated air flowing into these sterile stock rooms.

I can find in the engineering services guidelines that sterile store to corridor should be to 10pa and each pressure gradient step should be designed to 10pa however there is no clarity around:

* Should all four rooms be off the same AHU
* What is the minimal accepted pressure drop whilst a door is open or is the system to maintain 10pa across the door if open
* If there is a minimum pressure drop level, how long can this occur for before the sterile room is compromised

Can anyone advise/ help me with more useful advice as this is what we will be left with but I have my concerns and our builders are asking for evidence that what they have set up meets specs..I have concerns am I wrong?

Any feedback gratefully acknowledged as we have little time to respond and lodge a response

Kind regards

Lindy

Lindy Ryan

District Infection Prevention & Control CNC | Clinical Governance & Information Services MNCLHD

Level 1 Coffs Specialist Centre, Pacific Hwy, Coffs Harbour
Office 66911984 or Mob 0419 990 693 | lindy.ryan@health.nsw.gov.au
http://www.health.nsw.gov.au

General email enquires please use this email MNCLHD-InfectionControl@health.nsw.gov.au

[http://internal.health.nsw.gov.au/communications/e-signatures/images/NSW-Health-Mid-North-Coast-LHD.jpg]

Wise and humane management of the patient is the best safeguard against infection

(Florence Nightingale Circa 1860)

[cid:image005.png@01D6CF16.A659C720]

This message is intended for the addressee named and may contain confidential information. If you are not the intended recipient, please delete it and notify the sender.

Views expressed in this message are those of the individual sender, and are not necessarily the views of NSW Health or any of its entities.

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The use of trade/product/commercial brand names through the list is discouraged by ACIPC. If you wish to discuss specific reference to products or services by brand or commercial names, please do this outside the list.

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[Lalith Ramachandra]

Hello Lindy

I’m not a guru but will try and provide some guidance.

Do your sterile store rooms have terminal HEPA filters? And are the 4 rooms
connected?

The reason I ask this is because the pressure drop across a clean HEPA
filter is around 200Pa, and the pressure across a closed door maybe around
10Pa i.e. the pressure across the door is 5% of the filter and therefore
very unlikely to have any effect on the flow of air through the HEPA filter
and so to have any effect on the other rooms – the airflow into the room
would be relatively constant or increase very slightly.

When the door is opened the two pressures will equalise very quickly i.e.
the higher pressure will reduce. There will be mixing of air due to
turbulence etc.

Generally the sterile store will open to a relatively “clean” side and this
is not an issue.

If you need to maintain airflow from the sterile store to the other side,
you will need to maintain around 20Pa across the open doorway. This will
require an active control system and very very large quantities of air.
Generally not very practical (or required).

A better design would have been to have two rooms per AHU or 4 separate
AHUs – an increase in cost but generally would have been discussed during
the design phase.

When the door is open you cannot maintain the pressure differential unless
you have an active control system. I’m not aware of any guideline which
requires you to maintain the PD when the door is open.

Isn’t there a sterile barrier on all items in the store?

Hope this helps a little.

Regards

Lalith Ramachandra
LR Consulting Engineers (Mech Engineer)

PO Box 40968
Casuarina, NT
p 0401117423
e lalith.ramachandra@gmail.com

* Please, please, get vaccinated! *

On Fri, 24 Sept 2021 at 17:08, Lindy Ryan (Mid North Coast LHD) wrote:

> Hello SSD and HVAC engineering gurus
>
>
>
> My question is
>
>
>
> the current configuration of one of our facilities new clinic services
> buildings (about to be commissioned) is that all sterile stock rooms (4
> Rooms) are off the same AHU and therefore have no redundancy if the unit
> was to fail the would compromise all 4 rooms. The other problem with this
> design is that when the door is opened to the main sterile stock room it
> affects the other 3 rooms dropping the differential pressure across the
> doors below 7pa and if those door are open at the same time there would be
> minimal pressure with the potential for contaminated air flowing into these
> sterile stock rooms.
>
>
>
> I can find in the engineering services guidelines that sterile store to
> corridor should be to 10pa and each pressure gradient step should be
> designed to 10pa however there is no clarity around:
>
> – Should all four rooms be off the same AHU
> – What is the minimal accepted pressure drop whilst a door is open or
> is the system to maintain 10pa across the door if open
> – If there is a minimum pressure drop level, how long can this occur
> for before the sterile room is compromised
>
>
>
> Can anyone advise/ help me with more useful advice as this is what we will
> be left with but I have my concerns and our builders are asking for
> evidence that what they have set up meets specs..I have concerns am I
> wrong?
>
>
>
> Any feedback gratefully acknowledged as we have little time to respond and
> lodge a response
>
>
>
> Kind regards
>
>
>
> Lindy
>
>
>
> *Lindy Ryan*
>
> District Infection Prevention & Control CNC | *Clinical Governance &
> Information Services MNCLHD *
>
> Level 1 Coffs Specialist Centre, Pacific Hwy, Coffs Harbour
> Office 66911984 or Mob 0419 990 693 | lindy.ryan@health.nsw.gov.au
> http://www.health.nsw.gov.au
>
>
>
> *General email enquires please use this email *
> MNCLHD-InfectionControl@health.nsw.gov.au
>
>
>
>
> [image:
> http://internal.health.nsw.gov.au/communications/e-signatures/images/NSW-Health-Mid-North-Coast-LHD.jpg%5D
>
>
>
> Wise and humane management of the patient is the best safeguard against
> infection
>
> (Florence Nightingale Circa 1860)
>
>
>
> [image: cid:image005.png@01D6CF16.A659C720]
>
>
>
>
>
>
>
>
> This message is intended for the addressee named and may contain
> confidential information. If you are not the intended recipient, please
> delete it and notify the sender.
>
> Views expressed in this message are those of the individual sender, and
> are not necessarily the views of NSW Health or any of its entities.
> MESSAGES POSTED TO THIS LIST ARE SOLELY THE OPINION OF THE AUTHOR, AND DO
> NOT REPRESENT THE OPINION OF ACIPC.
>
> The use of trade/product/commercial brand names through the list is
> discouraged by ACIPC. If you wish to discuss specific reference to products
> or services by brand or commercial names, please do this outside the list.
>
> Archive of all messages are available at http://aicalist.org.au/archives
> – registration and login required.
>
> Replies to this message will be directed back to the list. To create a new
> message send an email to acipclist@acipc.org.au
>
> To send a message to the list administrator send an email to
> admin@acipc.org.au
>
> You can unsubscribe manually from this list by sending ‘signoff acipclist’
> (without the quotes) to listserv@aicalist.org.au
>

MESSAGES POSTED TO THIS LIST ARE SOLELY THE OPINION OF THE AUTHOR, AND DO NOT REPRESENT THE OPINION OF ACIPC.

The use of trade/product/commercial brand names through the list is discouraged by ACIPC. If you wish to discuss specific reference to products or services by brand or commercial names, please do this outside the list.

Archive of all messages are available at http://aicalist.org.au/archives – registration and login required.

Replies to this message will be directed back to the list. To create a new message send an email to acipclist@acipc.org.au

To send a message to the list administrator send an email to admin@acipc.org.au

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