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Introduction

Fires in oxygen enriched atmosphere start easily and are very intense, so the people injured suffer very serious burns, which are often fatal or cause very severe and prolonged suffering. Usage of Oxygen in hospitals are very common, During the pandemic COVID 19, the consumption of oxygen became very high, with a maximum consumption of 55 liters of oxygen gas for medical equipment Such as high flow nasal cannula and Ventilators at general ward and ICU. WHO estimates that at the current rate of ~ 1 million new cases a week, the world needs about 620,000 cubic meters of oxygen a day, which is nearly 88,000 large cylinders.

 

The Physical Properties of Oxygen

Oxygen Colorless & odorless gas Oxygen changes from a gas to a liquid at a temperature of -182.96°C (-297.33°F) when it takes on a slightly bluish color, Liquid oxygen can then be solidified or frozen at a temperature of -218.4°C, Oxygen does not burn, but readily supports combustion of other substances. It is capable of reacting with most metals and organic materials. The rate of reaction varies with the material and other conditions. The reaction may be slow (as in the rusting of steel) or rapid (as in combustion and explosion).

 

Oxygen Enrichment

Oxygen enrichment is a generic name for the hazards associated with gases and liquids containing oxygen concentrations greater than 21%.  Gases containing more than 21% oxygen are termed oxygen enriched gases. A breathing atmosphere containing more than 21% oxygen is termed an oxygen enriched atmosphere.  A liquid with greater than 21% oxygen is termed oxygen enriched liquid (for example, RL (rich liquid) is usually 35-40% oxygen)

 

Combustion in an Oxygen-Nitrogen Oxygen-Enriched

Complete Combustion: The filter paper strip burns completely. Incomplete Combustion: The filter paper strip burns for a length greater than 1 cm (2.54 in.) from a resistance wire igniter, but the flame extinguishes itself before the strip is completely consumed. Slight Combustion: The filter paper strip flames or smolders, but does not burn more than 1 cm (2.54 in.) from the resistance wire igniter. Non combustion: No ignition.

 

 

  Effects of Atmosphere Oxygen Content and Environmental Pressure on Flame Spread Rate 

Causes of Oxygen Enrichment 

  • Oxygen enrichment of the atmosphere can be the result of:
  • Leaking medical gas pipeline in the hospitals.
  • Liquid oxygen spill (Liquefaction) during refiling of liquid oxygen tanks.
  • Waste of oxygen during treatment the patients in ICU.
  • Waste of oxygen during Surgeries called (surgical fire- Airway surgical fire).
  • Leaking of oxygen gas cylinders during transporting of cylinder.

Sources of Ignition

  • Naked or open flames such as lighted cigarettes.
  • Static discharge.
  • AC spark plugs.
  • An electrical spark or fault causing overheating.
  • Heat sources (tea boiler…..)

 

Incident History  

  • In 12 May 2020 Fire was in Russian hospital kills 5 coronavirus patients, ventilator could be to blame.
  • In 13 June 2020 Fire was in Egypt, Tanta hospital in ICU have been evacuated patient in ICU.
  • In 28 June 2020 Fire was in Egypt, Badrawi hospital kills 7 coronavirus patients in ICU.
  • ECRI has announced in 2005 the risk of fire was reported during treatment the patient with oxygen.

 

 Fire-Stopping Techniques/ Oxygen Enrichment Precautions and Safeguards

  • Separation of combustible materials from oxygen enriched gas or liquid.
  • Separation of flammable materials from oxygen enriched gas or liquid.
  • A clear procedure for safety and security during refile liquid oxygen or cylinders.
  • Indoor air quality is very important to decreasing of the percentage of oxygen
  • Flash over barriers.
  • Fire drills and training are very important with medical protocol to evacuate ICU or OR patients.

 

Reference:

NFPA 99, NFPA 53 ,NFPA 55

Introduction 

Hospitals are the communities’ life support system in both times of crisis and in times of general healthcare needs. If something like a power outage occurs, vital power is still needed to keep life support machines and other necessary healthcare tools working in order to sustain human life. This is where the importance of generators comes in. When the power is out, a hospital almost always uses a backup generator to make sure that everything remains on and running. The need for generators in the healthcare market is one of absolute importance and a large percentage of standby power systems use the diesel engine. Diesel generator is a convenient independent fuel source and the compression ignition systems of diesel engines have a much higher thermal efficiency than the spark ignition system used by gas engines. However, one factor to be considered when selecting a diesel power source is the potential for “Wet Stacking.”

What Is Wet Stacking?

Wet stacking is a condition that occurs when your unused diesel fuel, accumulated moisture, and carbon particles are allowed to gather in the exhaust of your generator. This can happen for a number of reasons but usually results from diesel fuel not being properly burned off during use. As a result, a dark muddy liquid congeals in the generator’s exhaust stacks — hence the term wet stacking.

What Causes Wet Stacking?

When unburned fuel is exhausted out of the combustion chamber, it starts to build up in the exhaust side of the engine, resulting in fouled injectors and a buildup of carbon on the exhaust valves, turbo charger and exhaust. Excessive deposits can result in a loss of engine performance as gases bypass valve seating’s, exhaust buildup produces back pressure, and deposits on the turbo blades reduces turbo efficiency. Permanent damage will not be incurred over short periods, but over longer periods, deposits will scar and erode key engine surfaces. (Diagram One) Also, when engines run below the designed operational temperature, the piston rings do not expand sufficiently to adequately seal the space between the pistons and the cylinder walls. This results in unburned fuel and gases escaping into the oil pan and diluting the lubricating properties of the oil, leading to premature engine wear.

 

 

How to avoid wet stacking?

The best way to alleviate the effects of wet stacking is to apply additional load to the gen-set, increasing operating temperatures to burn off accumulated unburned fuel and carbon. The amount of minimum load varies per engine manufacturer; Also NFPA has guidelines to reduce the effects of wet stacking on backup power systems: NFPA guidelines in Level 1 and 2 applications require exercising the unit, at least monthly, for 30 minutes under either of two methods: (NFPA 110 8.4.2) (NCE Article 517) 1-Loading that maintains the minimum exhaust gas temperatures, as recommended by the manufacturer. 2-2-under operating temperature conditions and at not less than 30 percent of the EPS standby nameplate kW rating. Periodic Preventive Maintenance (PPM) Without proper maintenance generators are more susceptible to fuel problems like algae build up on the fuel system, clogged fuel injectors, wet stacking and dead batteries. These types of problems can even ruin your generator itself if they are let go for too long.

HealthCare Accreditation & Additional Conditions !

JCI-The Joint Commission on Accreditation of Health Care Organizations (JCAHO), the organization that accredits health care institutions, has taken this testing to a level beyond the NFPA. They require testing of 12 times per year with testing intervals between 20-40 days. Testing generators for at least 30 minutes under a dynamic load of 30% or greater of the name plate rating. Systems that do not meet the 30% load capacity have three options. 1. Increase the load to meet or exceed 30% of the name plate rating, 2. Maintain the minimum exhaust temperature as recommended by the engine manufacturer, or 3. Undertake load bank testing for a total of 2 hours continuous loading as follows: a) Load at 25% of name plate for 30 minutes b) 50% for 30 minutes c) 75% for 60 minutes.

CBAHI- central board for accreditation of healthcare institutions(KSA), they require testing this following: FMS.31.2.2 The hospital performs weekly test without load for ten minutes. FMS.31.2.3 The hospital performs monthly on load test for thirty minutes. FMS.31.2.4 The hospital performs full load test every three years on external load. FMS.31.2.5 The hospital generator starts normally without load for ten minutes. ,But without specific percentage load as mentioned in the NFPA 110 that should be 30% load.

NSR- National Safety Requirement Egyptian Healthcare Accreditation, they require inspection documents & preventive maintenance schedule, contracts & equipment, as well as testing results of generators, tanks &/or other key system to make sure of facility coverage 24/7. NSR 30- There is a well-structured & implemented plan for regular inspection, maintenance, testing & repair of essential utilities addressing at least the following: NSR30.1 Electricity; including stand-by generators , But without specific frequency and percentage load of the test as mentioned in the NFPA 110 that should be 30% load for 30 minutes.

Reference Codes and standards

NEC, primarily Articles 445 (Generators), 517 (Health Care Facilities), and 700 (Emergency Systems).

NFPA 99: Health Care Facilities Code.

NFPA 110: Standard for Emergency and Standby Power Systems.

Ahmed ElSayed Abudl Salam, Facility management and safety officer at king saud university medical city 

Tel:+966544368022

Email: unjumeau.a@gmail.com