Drill of the Month for December 2013

References: Pump Operator Student Manual, Maryland Fire and Rescue Institute; Pumping Apparatus Driver/Operator Handbook, IFSTA, 2nd Edition

Motivation:

Student Performance Objective: The student will demonstrate an understanding of the principles of drafting from a static water source and provide an adequate flow of water to a portable master stream device during practical evolutions, to the satisfaction of the instructor

Enabling Objectives

• EO 1-1 Describe the theory of drafting.
• EO 1-2 Describe the criteria for a good drafting location.
• EO 1-3 List common problems that can occur during drafting, their indicators and corrective actions to take.
• EO 1-4 Describe the basic operating practices when operating a pumper from draft.
• EO 1-5 Demonstrate proper drafting procedures during practical evolutions

Overview:

• Principles of drafting
• Considerations for a good draft site
• Common problems during drafting operations
• Drafting operating practices
• Practical application

1. Principles of Drafting (1-1)
1. Based on the principle of creating a negative pressure (vacuum) inside the fire pump and allowing atmospheric pressure on the water surface to force water up the suction tube into the fire pump.
1. Perfect vacuum provides 14.7 psi of negative pressure at sea level or 30 inches of vacuum.
2. A fire apparatus primer must be able to develop 22 inches of vacuum in 30 seconds.
3. 22 inches of vacuum is equivalent to 10.5 psi of negative pressure and will lift water approximately 24 feet.
4. The theoretical maximum lift with a perfect vacuum at sea level is 33.9 feet. The maximum practical lift for fireground operations is 20 feet.
5. Fire apparatus pumps are designed to supply their rated capacity at a lift of no higher than 10 feet.
6. The size of the suction hose / hard sleeve affects the maximum flow for a given lift.
7. The vacuum reading on the compound gauge is the basis for estimating the ability of the pump to supply additional GPM. Maximum flow from a fire pump at draft would be 22 inches of vacuum.


2. Criteria for a Good Drafting Location (1-2)
1. Amount of Water Available
2. Depth of Water source / Replenishment Rate
3. Site Accessibility (year round)
1. Stability of Ground
2. Height of Lift from Water Surface
4. Quality of Water
1. Sediment
2. Salt Content
3. Debris
4. Chemicals


3. Common Problems Encountered While Drafting (1-3)
1. Watch Your Vacuum Gauge
2. Unable to Obtain a Vacuum / loss of Prime
1. Air Leaks in Pump or Suction Hose
1. Check for loose hose connections
2. Check for open drain valves


3. Cavitation of the Pump / High Vacuum Reading
1. Blockage in the Strainer or Suction Hose
1. Check strainer for debris
2. Strainer in mud
2. Excessive Flow for Height of Lift
1. Reduce flow
2. Reduce amount of hose lines


4. Basic Operating Practices for Drafting (1-4)
1. Position Pumper as Near as Possible to Water Source
2. Apply Parking Break / Chock Wheels
3. Connect Strainer and Hard Suction Hose(s) with Airtight Connections
1. Barrel Strainer
1. Use ladder and/or rope to keep it off of the bottom and out of the mud
2. Need at least 18" of water above and below strainer to prevent whirl pooling
2. Floating Dock Strainers should be used for Shallow Water Operations


4. Engage Fire Pump / Put Vehicle Transmission in Proper Gear


5. Two Stage Pumps should have Transfer Valve put in Parallel (volume) or Series (Pressure) Position


6. Engage Primer Valve until Pump is Full of Water (approximately 15 - 20 seconds)


7. Increase Throttle Slowly until Pressure Gauge Reads at least 50 psi


8. Open Discharge Valve Slowly - Disengage Primer


9. Discharge Water back into Water Source to keep Pump Cool when not flowing Water


10. Set Relief Valve or Pressure Governor if appropriate


11. Watch Vacuum Gauge during Drafting Operation for possible Problems



5. Practical Application (1-5)
1. Utilizing Apparatus Provided, set up Drafting Evolutions from Various Static Water Sources as Appropriate:
1. Stream
2. Lake
3. Pond
4. Dry Hydrant
5. Portable Tanks
6. Underground Tanks (cisterns)
2. Use Portable Master Stream Device for Fire Flow
1. Students should check Nozzle Pressure with Pitot Gauge to Maintain Desired Flow
3. Rotate each of the Students through the Drafting Process using various Apparatus to insure Proficiency in this sometimes forgotten Skill.

Summary:

Student Performance Objective: The student will demonstrate an understanding of the principles of drafting from a static water source and provide and adequate flow of water to a portable master stream device during practical evolutions, to the satisfaction of the instructor

Review:

• Principles of drafting
• Considerations for a good draft site
• Common problems during drafting operations
• Drafting operating practices
• Practical application