(2) Procedures and Safety Precautions in Diluting
Hypochlorite Solution
(3) Procedures for using Hypochlorite Solution
(4) Disinfection of Filters in Ventilation System
(5) Procedures for Cleaning and Disinfection of
Computer Stations
(6) Procedures
for Disinfecting Offices and Office Equipment
(7) Procedures for Disinfection of Hostel
(8) Procedures
for Cleaning and Disinfecting Rooms in Hostels
(9) Procedures for Disinfection of Canteens
(10) Procedures for Disinfection of Buses
(11) Disinfection of Residence
(12) Procedures
for Disinfecting Lifts
(13) Procedures
for Disinfecting Garbage Collection Stations
Hypochlorite
solution, commonly known as ‘bleaching solution’, is a very powerful
disinfectant and with precautionary measures, should be safe to use.
Hypochlorite
solutions are available from supermarkets. Regular hypochlorite solution may contain up to 5.25%
hypochlorite and concentrated solution has 6% of the active chemical.
As an
alternate source, USEO has concentrated hypochlorite solution that can be
provided to users for disinfection (contact no. 26097958).
In areas with
heavy human traffic, a working solution of 0.1% hypochlorite strength should be
used for disinfection.
For domestic
uses, half of the above strength, that is, 0.05% hypochlorite solution should
be adequate.
a)
Remember:
1. Do not mix
hypochlorite solution with acids or alkaline.
2. Do not use hot
water to dilute the chemical.
3. Do not use
hypochlorite in undiluted form.
4. Store
concentrated hypochlorite solution in secure places and away from sunshine or
source of heat.
5. Always ensure
that the hypochlorite container has proper label.
6. Call USEO
(phone no. 2609 7958) for advice if in doubt.
b)
For your own protections:
1. Prepare
hypochlorite solution in place with good ventilation.
2.
Put on gloves, masks and eye protector.
3.
Prepare only the volume of diluted solution you can
handle for your work.
4.
Wash with copious amount of
water if your body has been in contact with hypochlorite solution
c)
Select a place with mechanical extraction (such as under
extraction fan in bathrooms or kitchens) for diluting hypochlorite solutions,
or simply work in open air if no mechanical ventilation is available.
d)
Put on gloves, masks and eye protector before
handling hypochlorite solution.
e)
Estimate the volume of working solution required and add
the required volume of water into a plastic container. One part of hypochlorite solution
should be diluted with approximately 50 parts of water to result in working
solution of 0.1% strength (for concentrated hypochlorite solution, the dilution
should be approximately 1 part in 60 parts of water). For example, if 5 liters of 0.1% hypochlorite solution is
needed, pour 5 liters of water into the container and add in approximately 100
milliliter of 5.25% hypochlorite solution.
f)
Gently pour the required volume of hypochlorite solution
into plastic containers filled with water and mix thoroughly. The mixing should be performed
carefully to avoid spillage or splashing.
Wash with copious amount of water if the body is in contact with
hypochlorite solution.
g)
The disinfectant is ready for use.
a)
Users must put on gloves, masks and eye protectors when
using hypochlorite solution.
b)
Use mop wetted with 0.1% hypochlorite solution to clean
the floor. All visible surfaces
including desk, benches, chairs, bookshelves, rubbish bins, window sills, doors
and windows should be wiped with cloth dampen with diluted hypochlorite
solution. Do not use excessive
disinfectant to result in disinfectant run-off after cleaning. After five to ten minutes, use another
piece of cloth dampened with water to wipe the surfaces again.
c)
Hypochlorite solution is for general
cleaning/disinfection purpose.
Computers and electronic equipment should be cleaned using other agents
(Section 5).
d)
After cleaning, wait for the wet surfaces to dry
completely before using the facilities again.
Filters in
ventilation system should be cleaned more frequently, preferably once every
week using disinfectants.
Where
hypochlorite solution is found not suitable for use with filters, tertiary
ammonium compounds or other types of disinfectant should be used.
Keyboards and
mouse of computer workstations, especially those intended for multiple users,
should be cleaned and disinfected periodically.
a)
Before cleaning, ensure that the computer and monitor are
turned off.
b)
Direct the suction nozzle of vacuum cleaner across rows
of keys on the keyboard to remove dirt/dust accumulated in between keys. Hand brush may be used to assist in
removing settled dirt/dust between punches.
c)
Use cloth dampens with ethyl alcohol to wipe clean the
keyboard and mouse. Do not use
excessive alcohol as the disinfectant is flammable.
d)
Wait until the residual alcohol has evaporated before
returning the computer for normal usage.
e)
Use 0.1% hypochlorite solution to wipe clean the surface of
CPU and monitor casings. Wait for
5 minutes and use another piece of cloth dampen with water to clean off
residual hypochlorite.
f)
The glass surface of video display terminals with cathode
ray tubes may be cleaned and disinfected using diluted hypochlorite solution,
after which, the surface should be wiped clean again with cloth dampened with
water.
g)
The video display surface of LCD monitor should be wiped
very gently using cloth dampen with water. No chemical disinfectant should be used to clean the delicate
surfaces of LCD monitors.
While floor in
offices are usually cleaned periodically by cleaners, furniture and office
equipment may not be included in normal cleaning cycles. Occupants should make their own
arrangements for cleaning.
a)
Floors with PVC floor tiles should be mop-cleaned using
0.1% hypochlorite solution. The
usual protective measure stipulated above must be followed.
b)
Floors with carpets should be vacuumed cleaned before
using carpet shampoo for further cleaning.
c)
Work desks should be cleaned and disinfected using 0.1%
hypochlorite solution and followed by cloth dampened with water.
d)
Keyboards and mouse of the computer station should be
cleaned periodically using ethyl alcohol while the CPU and monitor casing
should be cleaned using 0.1% hypochlorite solution followed by water as
described in Section 5(e) to 5(g) above.
e)
Other office equipment such as photocopiers and laser
printers should be cleaned following the procedures outlined in (6) (d).
a)
Use 0.1% hypochlorite solution to mop-clean the floor and
cloth dampened with the disinfectant to wipe clean surfaces in common areas
such as corridors, pantry and bathrooms on a daily basis.
b)
Resident’s room should be cleaned by the residents
themselves using 0.05% hypochlorite solution.
c)
Cooking utensils, cutlery and food containers should be
washed and disinfected using hypochlorite solution and followed by rinsing with
water.
d)
All rubbish bins should be emptied daily and the contents
properly disposed of.
e)
Filters of window-mounted air conditioners should be
taken out and washed to remove dust accumulated on it. After washing, the filters should be
dipped into 0.1% hypochlorite solution for 10 minutes, follow by rinsing in
water and drying, before returning to the filter slot in the air condition
again. Cleaning and disinfection
of the filters should be repeated every week.
f)
Prepare approximately 10 litres of 0.1% hypochlorite solution
(200 millilitres of concentrated hypochlorite solution in 10 litres of water)
in plastic buckets and flush down the toilet. Do not use the toilet for the next fifteen minutes.
g)
Prepare 1 litre of 0.1% hypochlorite solution
(approximately 20 millilitres in 1 litre of water) and pour down the washing
basin. Do not use the washing
basin for the next fifteen minutes.
Rinse off the residual disinfectant by turning on the water taps of the
washing basin. Similar procedures
should be repeated for other drainage openings.
(8) Procedures for
Cleaning and Disinfecting Rooms in Hostels
Students
should clean their own room, as there may be problems in handling their
personal belongings and properties by cleaners as well as difficulties in
making arrangement for the service.
Most of the
cleaning and disinfection works should follow the guidelines outlined
above. Cleaning tools and
disinfectant can be obtained from the hostel cleaners
(8a) Window-mounted Air Conditioner
a)
Put on masks and gloves. Before removing the filter from the window-mounted air
conditioner, ensure that it is turned off.
b)
Take the filter out and bring it to the cleaner’s basin
in the washroom. Turn on the water
tap and wash off the accumulated dirt from the filter. After washing, the remaining dirt
should be removed from the sink and dumped properly.
c)
Dip the filter in 0.1% hypochlorite solution for ten
minutes.
d)
Take the filter out and wash it again with water. Put the filter aside for drying.
e)
When the filter is thoroughly dried, put it back into the
filter slot in the air conditioner.
f)
The filter should be cleaned and disinfected on a weekly
basis.
(8b) Desks, Chairs, Wardrobe, Window Sill,
Windows, Blinds, Bed Frames and Bookshelves
a)
Before cleaning, all items should be removed from the
surfaces to be cleaned.
b)
Use 0.1% hypochlorite solution to wipe clean the
surface. Wait until the
disinfectant is dried up, and then repeat the process again using water.
(8c) Computer Station
a)
Before cleaning, ensure that the computer and monitor are
turned off.
b)
Direct the suction nozzle of vacuum cleaner across rows
of keys on the keyboard to remove dirt/dust accumulated in between keys. Hand brush may be used to assist in
removing settled dirt/dust.
c)
Use cloth dampens with ethyl alcohol to wipe clean the
keyboard and mouse. Do not use
excessive alcohol as the disinfectant is flammable.
d)
Wait until the residual alcohol has evaporated before
returning the computer for normal usage.
e)
Use 0.1% hypochlorite solution to wipe clean the surface
of CPU and monitor casings. Wait
for 5 minutes and use another piece of cloth dampen with water to clean off
residual hypochlorite.
f)
The glass surface of video display terminals with cathode
ray tubes may be cleaned and disinfected using diluted hypochlorite solution.
g)
The video display surface of LCD monitor should be wiped
very gently using cloth dampen with water.
(8d) Clothing, Bed Sheets, Blankets, Shoes
and Personal Items
Dirty and
soiled items should be washed immediately and not kept in student’s room for
prolonged periods. Whether
bleaching agent can be added during washing would depend on individual
items. Students should consult
washing guides or instruction of the items.
(8e) Ventilation Fans
a)
Make sure that the fan is turned off.
b)
Carefully remove the guard from the fan.
c)
Bring the guard to the cleaner’s basin in the
washroom. Turn on the water tap
and wash off the accumulated dirt from the guard. After washing, the remaining dirt should be removed from the
sink and dumped properly.
d)
Rinse the guard in 0.1% hypochlorite solution and let it
stands for ten minutes.
e)
Wash the guard with water and put it aside for drying.
f)
When the guard is thoroughly dried, put it back onto the
fan.
g)
The guard should be cleaned and disinfected on a weekly
basis.
(8f) Floor
a)
Ensure that the floor is free from electric bars and
other appliance before cleaning.
b)
Mop clean the floor with 0.1% hypochlorite solution.
c)
Do not enter into the cleaned area while it is still wet.
d)
The floor should be cleaned once per week.
a)
Use 0.1% hypochlorite solution to mop-clean the floor and
cloth dampened with the disinfectant to wipe clean surfaces in common areas on
a daily basis.
b)
Cooking utensils, food containers, and cutlery should be
thoroughly disinfected and rinsed.
c)
Staff working in canteens must wear masks. Those involved in handling food must
also wear gloves.
a)
Use 0.1% hypochlorite solution to mop-clean the floor and
dampen cloth to wipe clean the seats, metal window grille and handlebars, etc.
b)
Buses with sliding windows should be opened fully for
maximum fresh air.
c)
Buses without sliding windows should switch on mechanical
ventilation to allow maximum fresh air intake. Filters in the ventilation system should be cleaned and
disinfected every day using disinfectant.
While common
areas are handled by cleaners, residents staying in hostels and staff quarters on
campus should be responsible for cleaning and disinfecting their own
premises. In principle, the
guidelines listed under the sections on diluting and using disinfectant should
be used. However, the frequency of
cleaning and disinfection would depend on the actual need of the residents.
(12) Procedures for
Disinfecting Lifts
a)
Floors in lift must be mop-cleaned and disinfected with
0.1% hypochlorite solutions.
b)
The wall panels, including control panel, must be cleaned
and disinfected with cloth dampened with 0.1% hypochlorite.
c)
Wait for 5 minutes and use another piece of cloth
dampened with water to wipe clean the control panel and any other parts of the
wall panels made from metal.
d)
Lifts should be cleaned more frequently, and preferably
twice every day for obvious reasons.
(13) Procedures for
Disinfecting Garbage Collection Stations
a)
Prepare 0.2% hypochlorite solution (1 part in 25 parts of
water for regular bleach and 1 part in 30 parts of water for concentrate bleach)
outside the garbage shelter.
b)
Put on rubber gloves and masks and spray the plastic
rubbish bags inside the garbage trolley with the prepared hypochlorite
solution.
c)
Wash the external parts of the trolleys.
d)
Let the hypochlorite solution to drain off.
e)
Use 0.2% hypochlorite solution to wash the walls inside
the garbage collection stations.
Wait for fifteen minutes and hose-spray the walls again with water.