incidents involing Silos PN 807

Question 1

Define Silo

Answer 1

A container or tower, often cylindrical in shape, used for storage of silage,grain powders,pellets or crops

Question 2

Define silage

Answer 2

Any crop harvested while green for fooder and kept succulent by partial fermentation in a silo

Question 3

Name 8 Hazards that can be encountered at incidents in silos?

Answer 3

Explosion-
Entrapment in machinery-
Falling from height-
Silo contents-
Fire-
Construction 
Manual Handling-
Oxygen limiting Silos. 3:1

Question 4

Can personal enter a silo?

Answer 4

NO. Unless there is an immediate threat of serious injury or life loss. 6:6

Question 5

What level of line ops should be implemented?

Answer 5

Level 2

Question 6

What is the minimum lead role entering into silo

Answer 6

CM 6:9

Question 7

If flame is evident at the top of the silo this may indicate?

Answer 7

That the fire is not deep seated and it may be extinguished by the application of a suitable extinguishing medium to the affected area. 6.22 g

Question 8

Define Explosion

Answer 8

many of the contents stored within a silo produce a fine dust. When a heat source is put to this dust it can cause a explosion. Also other contents produce flammable gasses. These gasses at the right mixture can also cause an explosion.

Question 9

Define Entrapment in machinery

Answer 9

Silos usually have machinery which often includes augers, screw feeders, conveyer belts, paddles, suction piping, and mixing blades both externally and internally. These create a risk of severe injury or death.

Question 10

Define Falling from height

Answer 10

some silos exceed 30 metres. Personnel and/or equipment could fall inside or outside of the silo. Fixed external ladders may not be maintained in a useable condition or may be slippery.

Question 11

Define Silo contents

Answer 11

the nature of the goods stored within silos may create a toxic, flammable, oxygen deficient or explosive atmosphere. Opening up a hatch or door may create an explosive mixture.
The contents may act in a “fluid” manner and may not be weight bearing. Firefighters should also be aware of the contents “bridging”, this is a phenomenon whereby a seemingly solid material is only a bridge over a void where the contents have collapsed or have been emptied from below. Both of these could result in a Firefighter becoming entrapped resulting.

Question 12

Define Fire

Answer 12

When involved in a fire or suspected fire, opening any doors or hatches could result in a heat blast, injuring personnel that are in direct line of the opening.

Question 13

Define Construction

Answer 13

The nature of construction makes access/egress from silos extremely limited and natural light and ventilation virtually non-existent. Working in restricted spaces creates a risk of physiological and psychological stress.

Question 14

Define Manual handling

Answer 14

the rescue of casualties and the movement of equipment within a confined space increases the risk of muscular-skeletal injuries.

Question 15

Define Oxygen limiting silos

Answer 15

(h) Oxygen limiting silos or controlled atmosphere silos have a greater risk of backdraught or explosion when they are involved in a fire.

Question 16

4. 2 Station/watch managers should be aware that many large building sites use silos to store building materials and they need to ensure that all structures incorporating silos within their stations ground are visited, and a 7(2) d carried out and information gathered in accordance with Policy
5. 3 Particular attention should be paid to the following:

Answer 16

(a) Contact information for site engineer or other responsible person for information and plans.
(b) Type of silo, contents and associated hazards, such as machinery.
(c) Access and egress for pumping and specialist appliances, assessing hard standing, height clearance, restrictions or obstructions.
(d) Machinery/power isolation points.
(e) Water supplies, suppression systems or fixed installations for firefighting.
(f) Specialist equipment on site.
(g) Entry, exit points into silo.

Question 17

4:7 Under no Circumstances should?

Answer 17

crews enter a working silo or work beneath the silo during training.

Question 18

5:1 The incident commander must check for?

Answer 18

for all available hazard signage on entrance to the site, those displayed on the silo and any surrounding risks.

Question 19

6.1 The IC should remain at

Answer 19

ground level, unless pre-planning identifies a more suitable location.

Question 20

6.5 Consider the requirement for additional resources including:

Answer 20

(a) Fire Rescue Units (FRU), for specialist line rescue, cutting/lifting equipment and air monitoring equipment, or other specialist equipment.

(b) aerial appliance for improved access and egress or as an inspection platform and water
tower (see appendix 2).

(c) Hazardous materials and environmental protection officer (HMEPO), Rapid Response Team (RRT) or scientific advisor (SA) to monitor and advise on the environment and conditions within and immediately outside the silo.
(d) Tactical advisors:
(i) USAR (UA).
(ii) Technical rescue advisor (TRA).
(iii) Bulk media advisor (BMA).
(iv) Hazardous Material & Environmental Protection Officer (HMEPO)

Question 21

6.6 Personnel must not enter a silo

Answer 21

unless there is an immediate threat of serious injury or loss of life.

Question 22

6.7 Before personnel are committed into a silo, the IC must consider whether:

Answer 22

(a) There is a safer option for undertaking the required task.
(b) All practicable steps have been taken to remove or mitigate prevailing hazards, such as shutting down plant machinery, isolating power supplies and any self-actuating control devices.
(c) Safe access and egress can be maintained.
(d) Personnel have sufficient skills and equipment to undertake the whole task or whether additional resources will be required.
(e) There is adequate light and ventilation inside the silo.

Question 23

6.8 If a decision is made to commit personnel into a silo, the IC must implement the following:

Answer 23

6. 8 If a decision is made to commit personnel into a silo, the IC must implement the following:
   (a) Seek advice from a responsible person and/or the technical rescue advisor (TRA) before operations commence.
   (b) Implement Level 2 line operations.
   (c) Appoint and brief safety officers before personnel enter the silo.
   (d) Personnel must be fully briefed on their task, how this relates to the overall plan for the incident and all relevant safety considerations.
   (e) Appropriate DIM equipment is used to confirm safety of atmosphere.
   (f) Only the required number of personnel and equipment necessary to undertake the task should be committed into the silo.
   (g) Vehicles and staff have been be prevented from tipping in contents at any access points.

Question 24

6.9 Crews entering into a silo must be lead

Answer 24

By a crew manager as a minimum.

Question 25

6.15 If the silo has a discharge control mechanism,

Answer 25

it must be in the closed position. This mechanism
may be manually, mechanically or electronically operated. This will prevent contents from being discharged and injuring persons within the silo. A firefighter must be nominated, fully briefed and remain adjacent to the mechanism at all times throughout the incident to prevent it from being

Question 26

6.17 A thermal image camera (TIC) may help to locate casualties; however it must be remembered that

Answer 26

the TIC is not certified as intrinsically safe and any risk of explosion should be eliminated before use.

Question 27

6.21 When silos are involved in a fire, there is a risk of explosion, before attempting to commit any crews into the hazard area, the IC must first assess this risk in conjunction with:

Answer 27

(a) Expert advice and information gathered from the on site responsible person.
(b) Information received from HMEPO, RRT, SA.
(c) Any relevant hazard warning signage.

Question 28

6.22 Fires in silos may be protracted lasting several days, the IC should therefore consider a methodical approach to firefighting tactics and consider:

Answer 28

(a) The use of any on site specialist equipment or fixed installations.
(b) The establishment of a hazard zone and safe working area.
(c) Where a thermal image camera, or fixed temperature gauge indicates a rapid rise in temperature, this is an indication that the fire is beginning to involve the entire contents of the silo. In these circumstances crews should be withdrawn from the hazard area.

(d) The selection and application of a suitable extinguishing medium. Foam and water jets may
not be able to penetrate and extinguish a fire where the contents are compacted.

(e) Preventing spread of fire to other areas using covering jets and/or shutting ducts and chutes that lead to adjacent structures.
(f) Any ventilation within the silo must only be undertaken on the orders from the IC.

(g) If flame is evident at the top of the silo, this may indicate that the fire is not deep seated and
may be extinguished by the application of a suitable extinguishing medium to the affected area.

(h) If there is a need to decant or unload the silo. As the contents are discharged, crews should use covering jets to damp down and extinguish any burning material as it emerges from the silo.
(i) If hatches are opened crews must have appropriate extinguishing media in place and ensure

that they are not positioned in front of hatches as they are opened. These should only be opened once a risk assessment has taken place.

(j) In extreme circumstances, it may be necessary to cut an opening in a silo. This may impact on silo stability and worsen fire conditions due to the entrainment of air. This must only be carried out after seeking advice from the on site specialist representative, and once sufficient firefighting media is in place. There is an increased risk of explosion when cutting into a silo and this should only be undertaken when an explosive atmosphere can be fully discounted and any additional control measures are implemented.
(k) The application of water or foam may cause the contents of a silo to swell. This has the potential to cause structural collapse of the silo due to an increase in weight ,volume and pressure on the internal walls.
(l) Aerial appliances may be utilised as a water tower or to improve access and egress.

(m) Fires in oxygen limiting silos are rare, however when there is a fire in the silo, these pose a
greater risk of explosion. An alternative method of extinguishment is to close all doors and hatches and starve the fire of any remaining oxygen. This course of action must only be undertaken after consideration with the onsite responsible person. The introduction of water or foam into these silos may entrain air and increase the fire intensity or risk of explosion.

(n) Environmental issues arising from firefighting actions or water run-off.