Autoclave for Rural India
teesta das 7th semester product design GDPD guide: Gourab kar, Bhaskar Bhatt
CONTENTS
Methods of sterilisation Sterilization describes a process that destroys or eliminates all forms of microbial life and is carried out in health-care facilities by physical or chemical methods. Steam under pressure, dry heat, EtO gas, hydrogen peroxide gas plasma, and liquid chemicals are the principal sterilizing agents used in health-care facilities. Sterilization is intended to convey an absolute meaning; unfortunately, however, some health professionals and the technical and commercial literature refer to “disinfection” as “sterilization” and items as “partially sterile.” When chemicals are used to destroy all forms of microbiologic life, they can be called chemical sterilants. These same germicides used for shorter exposure periods also can be part of the disinfection process (i.e., high-level disinfection).
Sterilization by steam Steam sterilization is a recommended method for reusable medical instruments like needles and syringes (provided they are made of glass or ‘autoclavable plastic’.The autoclave should be operated for atleast 15 minutes after the load achieves a temperature of 1210C( 250oF) equivalent to a pressure of 1 atmosphere above atmospheric pressure, and after water vapour saturation.The autoclave must not be overloaded.
Commercial sterilisation recommends 121 degree celsius which is produced by maintaining a pressure of 15 psi and for sterilising the spores, the temperature of the container must be held for 15-20 minutes.
Sterility assurance level (SAL)2 is a term used in microbiology to describe the probability of a single unit being non-sterile after it has been subjected to the sterilization process. For example, medical device manufacturers design their sterilization processes for an extremely low SAL - “one in a million” devices should be nonsterile. SAL is also used to describe the killing efficacy of a sterilization process, where a very effective sterilization process has a very high SAL. In microbiology it’s impossible to prove that all organisms have been destroyed because: 1) they could be present but undetectable simply because they’re not being incubated in their preferred environment and 2) they could be present but undetectable because their existence has never been discovered. Therefore SALs are used to describe the probability that a given sterilization process has destroyed all of the microorganisms.
The post-surgery infection rates are very high in developing countries where most of the infection is caused by unclean surgical instruments. Each surgical procedure involves the contact of a surgical device with the patient’s sterile tissues or mucous membranes. The major risk of such procedure is the introduction of pathogens which might lead to infection .Failure to properly disinfect or sterilize equipment can risk person-to person transmission of viruses like Hepatitis B. Disinfection and sterilization are essential to ensure that the medical and surgical instruments do not transmit any infectious pathogens to patients.
Definition and note from ISO 11139: 2006 (1) Sterility Assurance Level (SAL) – probability of a single viable microorganism occurring on an item after sterilization. Note: The term SAL takes a quantitative value, generally 10-6 or 10-3 When applying this quantitative value to assurance of sterility, an SAL of 10-6 takes a lower value but provides a greater assurance of sterility than a SAL of 10-3 http://whqlibdoc.who.int/aids/WHO_AIDS_2.pdf http://www.microbiologyforum.org/PMFNews/PMFNews.14.05.0805.pdf Guidelines for disinfection and sterilization in healthcare facilities, 2008
The autoclave An autoclave is an instrument used to sterilize equipment and supplies by subjecting them to high pressure saturated steam at 121 °C for around 15–20 minutes depending on the size of the load and the contents.It was invented by Charles Chamberland in 1879,although a precursor known as the steam digester was created by Denis Papin in 1679.The name comes from Greek auto-, ultimately meaning self, and Latin clavis meaning key — a self-locking device.
Basic Parts
1.Body of the autoclave 2.Chamber jacket, to contain packages to be sterilized 3.Metal base to support basket, drums above water 4.Drain tap 5.Lid 6.Tap or valve to allow purging of air during heating phase 7.Pressure Valve: Regulates the pressure by allowing excess vapour to escape 8. Safety valve 9.Pressure Gauge 10. Door gasket 2.
5.
10. 3. 1. 8. 9. Denis Papin’s Steam digester
7.
4.
Small autoclaves used in India
How does it work?
USER INFORMATION
1. The Use of Steam: either by a separate steam generator, or by chamber purging and steam conversion in the chamber itself.
2.Heating the water, either by direct contact to flame or electrical resistance surrounding the pressure chamber
3.The customary sterilization only takes place at a temperature of 121oC and 15 psi, when in order to sterilise the equipment off the spores, it is essential to hold the temperature in the chamber for a minimum of 15 minutes.
4. Sealed bacteria availiable as commercial strips are pasted on the autoclave drum, to check for a visual feedback if the load is sterilised or not, the microbial survival or spore formation probability value is 10-6.
Sterilization Cycle Phases 1.Purge 2.Pre-vacuum 3.Sterilize 4.Cool
Primary users: Paramedical and maintenance staff in hospitals. clinic assistants of dentists Secondary Users : Doctors, sister nurses Tertiary Users: Suppliers and dealers, Repair mechanics Information Collection methodology: Shadowing the paramedic staff Face to face interviews with doctors Informal interview keeping a prepared questionnaire in mind Internet correspondence with doctors practicing in remote areas Subject areas visited: -Munshi Nursing Home, Shantivan -Orthopedic Department, Civil Hospital -AAshu Dental Clinic, Navrangpura -Dev Hospital, Jamalpur -Interview with Mr Jaimin Vakil ,who works for the Central Sterilisation ad Storage Department in Johnson &Johnson as the Design and Sales consultant.
CAse study 1: Orthopedic Trauma and Emergency Department, Civil hospital, Ahmedabad
CASE STUDY 2: Munshi Nursing Home, Shantivan, Ahmedabad
Steriliser used: Fully automatic autoclave Manufactured by Hanshin, Korea
Steriliser used: Pressure Cooker type, top load, high pressure steam steriliser for linen and gynaecological surgical instruments. Locally Manufactured
FEEDBACK: The nurse who uses the autoclave with the OT, reveals her technology barrier -Very big to be installed in the theatre, hence kept in a room in close proximity of the OT -There is an increased exposure time during forcep transfers from tray to drum -She prefers a simple autoclave with a stand in the OT, where can easily transfer the instruments to the doctor.
OBSERVATIONS: -Autoclaving is done twice a day because they have enough spares -Staff finds the device heavy when required to be shifted around -Repair mechanic is difficult to find and call hence several spoilt autoclaves found around -No drying cycles in such sterilisers -Condensate leakages and calcination -Cognitive feedback for users is improper.
Pressure gauge on lid top (top) Sterilisation stickers on drums (below)
Display and control panel
Tray and steam vents
Water inlet (top) Door and door gasket (below)
Door locking pedal
Full view of autoclave
Autoclave front view : door closed (top) Autoclave front view : door opened (below)
Lid Locking bolts
Hinged lid with drum inside the chamber
Calcination around the steam vents
Gynaecological surgical instruments
Spoilt autoclave
CASE STUDY 3: Dev Hospital, Jamalpur, Ahmedabad
CASE STUDY 4: Aashu Dental Clinic, Navrangpura, Ahmedabad
Steriliser used: Para-formaldehyde tablet in an acrylic chamber for heat sensitive instruments likes scopes and platic tubes Locally Manufactured
Steriliser used: Enclave Autoclave Manufactured by: Dibya industries, New Delhi, GDP Dental Products
OBSERVATIONS: -Formalin vapours used to fumigate the OT every week -Formalin tablets used to sterilise heat sensitive instruments used during operations, when the the assistant is supposed to pass the instruments from inside the chamber to the doctor as per requirement. -Highly irritant to the eye
OBSERVATIONS: -Autoclave kept in isolation from working space -Lab assistant adapted to the DISCO panel afetr the clinic discarded the pressure type autoclave - The load(steel instruments) are sealed in packets, while plastic are wrapped in cloth -Condensate leakages after use
Water poured into chamber Photo cluster above: Formalin tablets and Acrilic chamber box with instruments inside right: Tablets kept between the insruments in the trays,
Display and controls
Front view of device
Right (from top to bottom): instruments wrapped in cloth and gauze in steriliser drums, used only for storage ; cripping and packing the instruments before autoclaving ; packaged instruments placed in trays inside the autoclave
Case study 5: Dr Sanjeeb Deb, Borsilla Tea estate, Assam
Excerpt from the interaction with Johnson & Johnson official Dr. Jaimin Vakil, Centrail Sterilisation and Supply Department of J &J
Questionnaire prepared to understand context and scenario: Q:Which method of sterilization is suitable for your instruments on the field ? a)STEAM b)Liquid(Gluteraldehyde,cidex) c)Formaldehyde tablets A:We use both steam and liquid methods.
There are different methods and processes of sterilisation. 1. Steam Sterilisation: Most widely practised in all nursing homes, hospitals, dental clinics, veterinary hospitals. Possibly the best methods of sterilisation but does not sterilise all kinds of materials. Problem area lies in scopes and calcinations of water and also a cold water syndrome.The cheapest one available is for 1 lac. Many steam sterilisers used are not the right kind of steam sterilisers where the process uses pre and post vacuum stages. Most are the geyser type, which does not meet the standard.
Q: What are the basic surgical instruments that you need to keep? A: Basic surgical instruments are surgical knives, artery forceps, needle holder, mosquito artery forceps, sponging holding forceps, suction apparatus, pointed forceps, dressing drum ,scissors ,ENT sets oxygen cylinder etc.
2. Gas Sterilisation: using Ethylene Oxide gas. It is a low temperature and High pressure technique, that takes 7-8 hours for one cycle to last. All items gas sterilized have to be given aeration time period. The method is carcinogenic in nature, hence users must be extra cautious while following the manufacturer’s manual.ETO sterilisation is a method used to sterilise materials that cannot be steam sterilised, like plastic, battery operated instruments, lens instruments(scopes)
Q: How many spares do you keep? A: We keep 1 spares. Q:Do you sterilize gauze and linen for use each time on the field? A: In Hospital setup we sterilise the instruments in each time but in camps far from the Hospital we cannot. Q:Is it a practice for you to autoclave instruments at your clinic and carry it in a drum for use later? A: Yes we autoclave the instruments in clinic & carry it in dressing drum later. Q: Has there been any case or situation when you have had to deal with patients back to back for operations? A: Yes in camps we have to deal with the patient back to back. “In case of Medical camps the scenario is worst. Peoples are informed on loudspeakers or by other media so that to gather them in a bulk quantity. In such camp we have to treat more than 500 patients by a single doctor within a stipulated time. We organise laparoscopic sterilisation (tubectomy) camp twice in a year at our tea garden. in such operation one Surgeon have to operate at least 50 surgeries. Sterilisation is the main part in such type operation camps...” Q: Is electricity a problem in your areas? A: Electricity is the main problems in remote areas.
3. Formaldehyde Sterilisation: Formaldehyde vapours are used extensively to disinfect and fumigate the Operation theatres. Formaldehyde tablets are also used in acrylic chambers where doctors keep scopes, catheters, plastic instruments etc. The use of this method is highly dangerous for the fume in itself is highly carcinogenic, but it is cheap and readily available. Dr Sanjib Deb He is an MBBS Doctor and has been practicing since 1999. He started with working in a nursing home in Dibrugarh and is now going to complete his 11 years of service in the tea garden hospital. He is accompanied by doctors and surgeons from nearby towns and tea estates for medical camps.
Q:Do you have an assistant to help you during proceedings? A: We have the assistants like Pharmacist, Nurses, Laboratory technicians Etc. Q: .What measures do you take between the time of the first operation and lunch-when you need sterilized instruments again? A: During back to back operation in field we sterilse the instrument in autoclave in hospital then we carry in drum to the site of operation then we use steam & liquid sterilisation method .In between first & last operation we use only liquid sterilisation(povidine iodine solution)only to sterilise.
4. Plasma Steriliser: using hydrogen peroxide. The compound is in a concentrate of 50% in the chamber. It is a low temperature technique. Time taken for the process is 20-55 minutes. It is good for all heat sensitive equipments and others except for linen. The process is safe for the environment as well. Under this category of sterilisation come: ozone sterilisation and gamma sterilisation as well. The cancer Hospital in Ahmedabad is using the plasma sterilisers of 30 litre capacity. It is called “STERRAD”. It is the next technology to hit the market, where the smallest is going to be 30 litres costing 20-25 lacs and going to 100 litres costing 60 lacs.
Technological issues with Steam sterilisers
Comparitive analysis between other methods of sterilisation Conditions
STEAM UNDER PRESSURE
ETO GAS STERILISER
Material
Linen, surgical instruments
Plastic, Linen, plastic,lens,scope scopes,lenses
plastic
Safety
Unsafe for heat sensitive instruments
carcinogenic
Safe
Carcinogenic
Time
1 hour per cycle
7-8 hours per cycle
20-55 minutes
fastest
By-products
Water condensate
Lengthy cycle
Water and oxygen
ozone
30 litres
30 litres
-
20-25 lacs
Rs 125 per bottle
The use of the autoclave is very universal. However, in the real context, it is not exactly very safe. Most of the equipment is all put together for autoclaving. 1. Not appropriate for heat sensitive instrumnets like those of plastics, battery operated devices, lens instruments, scopes. 2. Deposition accumulates at the lens ends, resulting in a damage of expensive equipment. (above said is an excerpt from notes taken during a face-to-face interview with Mr Jaimin Vakil, CSSD department official at Johnson and johnson.
Minimum 20 litres capacity available Cost
2-2.5 lacs
PLASMA steriliser (hydrogen peroxide)
*http://www.ijo.in/article.asp?issn=0301-4738;year=1998;volume=46;issue=3;spage=174;epage=175;aulast=Sharma Comparative analysic charted upon the knowledge of exisitng methods of sterilization.
PARAFORMALDEHYDE TABLETS*
1. Preparation of instruments by cleaning with detergents and brushes. 2. Instruments are placed in drums and trays, as wrapped or sealed instruments and the drum holes are opened.Sterile stickers are put on the drums. 3.Water tank is filled upto the level indicated.
4.Drum and trays are placed in the pressure chamber.
5.The lid/ Door is locked mechanically, each bolt is tighly turned.
Task analysis
Deductions and learnings 1. Most doctors prefer to use the steam steriliser for their use. Reason: cheapest technology available and non-availability of other autoclaves in the market 2. Paramedical staff finds it uncomfortable to use a display and control that is complex looking, however, they adapt over time. 3. The devices used currently are all very bulky and heavy, even to be shifted around the OT periphery, also if they are availiable in smaller sizes for tabletop purposes. 4.Repair of a machine always happens in a week’s duration or more becasue mechanics are never easily available. 5. PLasma sterilisers are most effective nd one fo the best ways of sterlising instruments 6. Different materials should be takn care by being sterilised with different techniques available. 7 Para-formaldehyde tablets are one of the most widely used sterilisation techniques although it is carcinogenic in nature because it is one of the fastest methods of sterilising.
Initial Design brief:
6.Device is switched on. The purging of ambient air starts. 7.When steam starts releasing from the pressure valve, it is tightened shut. The sterilization cycle starts. and after 45 minutes -1hour: 8. The bolts on the lid are unscrewed. 9.Lid is opened
10.Drums are removed and drum holes are shut again. 11. Water is drained out if its the only cycle, else, the next shift of load is placed inside.
To make a small autoclave for doctors who work in remote areas and perform surgeries on the spot as big hospitals are difficult to access. The case is handled by the doctor himself over there. The scenario is also inclusive of times when medical camps are set up when the doctor has to operate back-to -back situations right there and then. For such a scenario, it is found that there is a need of proper sterilized instruments while operating, in order to avoid transmission of diseases. Thereby arises the need for a portable steam autoclave in the field where an assistant will have to repeatedly keep loading and autoclaving the instruments required per operation. It is also found that such places are economically under-developed. Hence, there is a greater need for a device that allows repetitive use of instruments in medical camps.
Initial sketches and brainstorming
Proof of concept: Pressue coooker is the most easity available and cheapest method of testing the concept. An average pressure cooker also releases pressure at 10 psi, which if kept long anough would autoclave as well. There are some pressure cookers that come with the pressure gauge screwed to it on the lid, enabling the pressure checking.
Fuel test: NID back gate, small community Deopani Tea garden hospital, Assam Pressure Chamber test : NID mess kitchen Deopani Tea Garden hospital, Assam Concept check : Autoclave tape
Pressure cookers used for proof of concepts:
2 ltr pressure cooker
35 ltr pressure cooker with side handles and pressure gauge. Pressure range: 10-12psi
Autoclave tape test
20 ltr pressure cooker with side handles, pressure gauge and temperature gauge. Addittional weight to increase pressure range till 15-20 psi
NID MESS
Fuel test: pressure cooker on a chullah
Pressure chamber test 1
Location: NID mess kitchen Single drum test using kitchen pressure cooker.
Location: small community behind NID Tested with wood and some plastic and available resources.
35 litres pressure cooker taken
The Wood takes 5 minutes to start burning properly and another 5 -7 minutes to heat up and the chamber. The pressure valve releases steam in the next 4-5 minutes. The chamber can be opened in 1-2 minues of the pressure release and contents maybe be removed thereafter.
3 glasses used as stand for drum and water height
Bigger the size, more difficult is it to close
Used gas as fuel
1st whistle at 7 minutes 46 seconds
Difficult to lift off the fire immediately
External cooling required to open immediately
whistle released manually to neutralise pressure inside
Lot of water required for external cooling
Drum toppled off the stand in boiling water
Need to fix a stable stand
Need to drain water from inside the drum
Pressure chamber test 2
Location: NID mess kitchen Single drum test using kitchen pressure cooker.
35 litre pressure cooker used again
Rice “channi� used as stand
1st steam release at 6:05 mins
4 whistles : steam releases
Bare hands touching hot drum is unsafe
Container size bigger than the drum allows more handling
Autoclave strip used to check efficacy of process
Autoclave needs external cooling for immediate recovery
Water filled again iinto container
Pressure chamber test 3
Difficult to close interlocking lid
pressure range of cooker is till 10 -12 psi
manual pressure release through whistle
autoclave strip shows negative
Drum pressurised again
autoclave strip changes colour but after exposure
Location: NID mess kitchen Single drum test using kitchen pressure cooker with additional 50 g weight on the whistle: 2 magnets of 20g and 30 g used
single drum much smaller for a 35 litre container
water needs to be filled carefully from the side if the drum is kept first
35 litre pressure cooker used with increased whistle weight of 20 g
since weight was placed below the whistle, release not happening
pressure release after removing weight
changed the weight location to top of whistle and incresed weight to 50g
first whistle at 4:18 mins( faster due to pre-heated water)
handling heated weights with tongs
whistle drops with pressure release
pressure release happened without any weight
complete pressure release by placing the tongs against the whistle
vertical placement of weight on the whistle
Pressure chamber test 4
using whatever cloth to lift the p.c. with the handles
holding the drum directly with the hands immediately post autoclaving
handling the heated container and carrying it around is a dangerous
Lid opened and drum allowed to cool slightly in the container. Container much bigger than the drum
autoclave strip shows positive black stripes
Location: NID mess kitchen Using a 2 litre pressure cooker and a small tiffin with cotton gauge inside it
2 liitre pressure cooker used
overlapping flames because of wide contact plate
black soot on the external
first whistle with release of water and foam
frothing around the whistle
froth falls till the contact plate
allowing 21 whistles makes excess carbon deposits
after fuel supply is shut, contents left to incubate
instruments inside are moist and soggy.
Take ways: 1. water level test 2. steam relese counts
change in water level from 1/2 to 1/8th of chamber
totally autoclave time : 39 mins
successful autoclaving!
Pressure chamber test 5
Pressure chamber test 6
Location: NID mess kitchen Using a 20 litre pressure cooker and an autoclave drum and sticker to attest the test
Behind Juma Masjid, Bartan gali, Teen darwaza, Ahmedabad
New pressure cooker
new p.c. steam release leaves calcination on lid
New fittings: analogue pressure gauge and temperature gauge
excess water loss
excess water inside, froths outside
sucessful autoclaving!
steam release clouds the gauge
Confirming the number of whistles Location: NID mess kitchen Using a 20 litre pressure cooker and an autoclave drum with autoclave stciker to attest the test
Pressure chamber test 7
Confirming the number of whistles Location: NID mess kitchen Using a 20 litre pressure cooker and an autoclave drum with autoclave stciker to attest the test
Ideation
Handles and handling
Stack Effect
Exploration for Burner Principle test: To check draft of air when burning
Low budget prototype built and taken for field testing
Fuel feeding inlet combustion chamber
Insulation jacket
biggest size, equi-distant holes: 10mm
8mm holes for cross draft
5mm holes for cross draft
smallest holes for efficient fuel burning Side view Portoclave
Top view Portoco-
Deopani Tea Garden Hospital
Borsilla Tea Estate Sivasagar District, Assam PORTO-CLAVE | 27 FEB-1 MAR 2012
-The tea-garden hospitals are small and very basic in nature to assist the medical-health of the plantation workers and their families. For most serious cases, patients are mostly taken to either Amgurie (40 minutes by road) or Sibsagar (1 hour by road). -There are at least 2-3 deliveries in a day in the hospital or there are days when there are none. The hospital primarily functions as a maternity ward and a general check-up clinic. -Electricity in the garden is uncertain and trips throughout the day. -Due to the budget constraints of the company funding the hospital (Atmaram and Co.), the doctor has to resort to alternatives unjustifiable otherwise in urban set-ups.
Dr Sanjib Deb He is an MBBS Doctor and has been practicing since 1999. He started with working in a nursing home in Dibrugarh and is now going to complete his 11 years of service in the tea garden hospital. He is accompanied by doctors and surgeons from nearby towns and tea estates for medical camps.
Usage of a Steriliser and not an autoclave*. The steriliser costs Rs 2000-2300. It has to be replaced every 2-3 years because the filament gets burnt overtime. The steriliser is manufactured in Kolkata.
Non-availability of sufficient disposals.
The sterilisation is done using a betadine solution in the water and boiling the water.
Steriliser kept in a well-ventilated room, which is also their dispensing room.
*The steriliser is an SS container with a heating element under a tray over which water is filled and instruments are placed. The system is dependent on electricity and there is no display of any kind on this device. There are handles on either sides to grip and open the lid to check/add/remove the contents inside. The operator would simply place the instruments inside to sterilise and usually use disinfected forceps to remove instruments from the device onto a tray and then into a drum.
Tray used to keep the instruments instead of the drum.
Instruments are handled directly with the hand to place the instruments into the tray: could potentiallly be dangerous if the water is boiling.
Hospital kitchen
The process took longer because the gas intensity was lower than the mess. 8.5 minutes : Whistle 1 Pressure range : 21-13 psi. Temperature range :25-127 degrees. The entire process took 26minutes to start and pressure down. successful autoclaving!
Easy access to water inside the kitchen for washing/cleaning and filling
There is a gasoline connection in every government house. So even if its not electricity based, it can be a gasoline based device, as an alternative. Before the gaseline, they used to use wood/bamboo to light a fire and cook food. General obs.: Tendency to waste a lot of fuel.
The container was then transported to the doctor’s room where the attendant carried it easily because of the grip and (also because it was only a short distance), however, minding to keep it away from the body. No calcination deposits in the chamber or on the drum, indicating that the water available is not hard water.
Hospital Visits in Assam :
Ligiripukhuri Hospital
Hospital Visits in Assam :
Sibsagar Civil Hospital
10kms from Deopani. Autoclaves used like sterilisers for nursing instruments. Only the cloth is autoclaved with vapours. The other instruments are simply dumped inside and the water is boiled to sterilise the instruments. During any back-to-back operation, the water is kept boiling and the instruments are simply dropped and picked out of the steriliser for use and re-use. The instrument is kept for 30 minutes atleast. When the operation is on, it is important to pre heat and keep the water boiling already.
The Surgeon from this hospital accompanies Dr Sanjib Deb to the Medical camps and he carries a 50l autoclav to the field which is difficult to transport in MMUs. The portable autoclave used is extremely heavy to lift and move. Hence the doctors nowadays refrain from carrying them to the field and work with spare sets and on the spot disinfecting. Some doctors that are participating in medical camps, and cannot afford their own autoclave, usually would come to a civil hospital or any other private clinic or nursing to get his drums sterilised and ready to carry to the field.
Pressure chamber test 9
Confirming the outdoor scenario Location: Borsilla Tea Garden Hospital Using a 20 litre pressure cooker and an autoclave drum with autoclave stciker to attest the test
Inferences and learnings: •
Water should be below the level of the stand. The stand can be of any height accommodating the heating element and the drum inside the container.
• The lesser the water contact, the better is the autoclaving. Since it is not possible to make the process moisture-less, the moisture can be lesser. >>Maybe a heating lamp that gets charged as the chamber gets heated and then glows after the 7th whistle autoclaving is done. •
Fire guard/ Wind Guard to protect the container from rising flames and even the instruments fixed on the lid.
• Usability: Touching the handles post autoclaving is never an issue because of the material of the pressure cooker handle. However, the carbon soot may deposit on the handle over time and heating exposure. • Usability: There always has to be a complete pressure release to open the chamber. Even after the pressure gauge shows 0 psi, there is a minimal pressure inside the chamber that needs to be removed in order to open the chamber. •
Doctors/paramedical staff will only use it effectively if it works fast for back-to-back operations. Casualness while autoclaving is of no use.
•
Whistle counter as most times the whistle count is mistaken.
• Carry-able: Light /handles Even a small autoclave as small as a tiffin box works well for a doctor to autoclave cloth and cotton swabs and small instruments. •
Forcep-keeper: Forceps are used to remove instruments/drum from the chamber.
•
Charcoal maybe a good option.
• Time for the 1st whistle depends on the surface area of contact for heat. Firewood took 8 minutes roughly and gas takes roughly 7 minutes. However, for the firewood, the fire was enveloping the chamber while for gas there was greater temperature/heat loss from the chamber cover.
Graph noted for the final outdoor pressure chamber test
Final concept map
Charcoal Briquette: The smokeless story Basic charcoal is produced by burning a carbon-rich material such as wood in a low-oxygen atmosphere. This process drives off the moisture and volatile gases that were present in the original fuel. The resulting charred material not only burns longer and more steadily than whole wood, but it is much lighter (one-fifth to one-third of its original weight). Briquetting is the process of converting low bulk density biomass into high density and energy concentrated fuel briquettes. Charcoal briquettes are the next compressed version of Charcoal, wherein the Charcoal is in this case a main constituent, which is crushed and ground alongside a binder, mainly endemic to the region. After it is mixed with a binder, it is moulded through a press mould where a briquette is reproduced and then dried and stored. The briquette is an even more smokeless fuel whereas it gives a high temperature range than charcoal. The agricultural residues are produced in abundance after harvest of each crop in villages. Most of these residues are burnt in the open field. However using Biomass Charcoal Briquetting technologies, these residues, can be used for generating an alternative fuel which is cost effective and environmentally friendly. It can also add income to the family.
Interface and electronics
Mood board
Form Ideation
Sketchmodelling
Concept model: PORTOCLAVE with chulha base for wood fire burning
Concept model: PORTOCLAVE with simple electronics to call the attendant when process is ending
Concept model: PORTOCLAVE with a self standing instrument box and water level indicator inside pressure chamber
Concept model: PORTOCLAVE with an electric stove
Dimensions: PORTOCLAVE_lid
Dimensions: PORTOCLAVE_upper handle
Dimensions: PORTOCLAVE_upper handle with parts
Dimensions: PORTOCLAVE_pressure chamber with main handles
Dimensions: PORTOCLAVE_chulha stove
Dimensions: PORTOCLAVE_ electric stove