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Smooth Operator > Pumping > Flashcards

Pumping Flashcards

Pumping

1
Q

Describe Centrifugal pumps

A

Uses centrifugal forces - Moves water from the centre of rotation- construction consist of two main parts, the impeller and casing

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2
Q

Describe Impeller

A

Circular metal casing and rigidly keyed to a central shaft. Rotated by external power source- rotation causes water to discharge away from the centre-This flow causes a partial vacuum at the inlet, as a result This induces more water into the inlet- water from the inlet is picked up by the impeller vanes and is energised as it spins - Speed increases as it reaches the outer rim and is discharged at high velocity- as water enters casings, most of the kinetic energy becomes pressure energy Heat occurs if pressure cant be released

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3
Q

Describe Casing

A

Designed to reduce turbulence and friction - as water enters casing, the kinetic energy becomes pressure energy.- Achieved by reducing velocity- two methods used Volute and Guide vanes

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4
Q

Describe Volute

A

Snail shaped, simplest type of centrifugal pump casing- water from impeller, enters a passage and steadily increases in cross section until it reaches the delivery outlet- as a result velocity of water is greatly reduced- Converts kinetic (Speed) to pressure energy

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5
Q

Describe Guide Vanes

A

fixed vanes guides water along the correct path - aka a Guide ring or diffuser- reduces turbulences at the periphery of an impeller- allows for conversion of kinetic energy to pressure that starts at the Guide vanes and is completed by the Volute

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6
Q

Describe High Pressure Pumps

A
  • Connected to outlet of main pump - Impeller driven by different gearing so any revs will spin at much faster rate - HP pump supplies water to high-pressure hose reels only - designed to operation at pressures up to 4200kpa possible - Excess pressure relieved by kunkel valve
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7
Q

A device that houses two highly polished carbon/ceramic components known as faces. Its purpose is to keeps water in pump casting is known as?

A

Mechanical seal

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8
Q

What is the relationship between the head of the water and pressure?

A

P = H x 10

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9
Q

Describe the Tank to Pump Switch?

A

in the Open position the onboard (tank) water supply is used. - in the closed position and externalwater supply is used e.g. hydrant- Make sure its smooth - no water hammer - Leave tank to pump Open until tank is full then switch to off so you use external source

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10
Q

What is Cavitation?

A

When the pressure on the suction side of the pump falls below vapour pressure, local boiling and vapour bubbles form- They are carried to the eye (inlet) where the cavities suddenly collapse- This water implosion can break away small particles of metal - Eventually causes impellor to fail

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11
Q

Causes and indicators of cavitation?

A

Causes - Lift too high for the volume of water and pressure being discharged - Hose diameter too small for volume of water being discharged - Restriction or partial collapse of suction line - Water temp being pumped is too high - over-running supply Indicators - Sound of gravel passing through pump - engine revs increase - Shows negative pressure or moving towards negative pressure - Collector hose goes soft - Decrease in delivery flow and pressure

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12
Q

steps when the Emergency engine shut down button is activated?

A

Only use if absolutely necessary - Shuts down everything, engine, pump, all of it. To Reset: 1. Return throttle to idle 2. Select neutral 3. Disengage main and high pressure pump 4. Turn ignition off and wait 10 secs 5. Restart engine 6. Engage pumps 7. Select drive 8. Recommence pumping9. Reset Emergency engine shut down button

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13
Q

What is the average water pressure around hydrants in the ACT?

A

800 kPa

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14
Q

What is the maximum practical suction lift for draughting in the ACT?

A

7 metres (minus 70kpa on the gauge)

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15
Q

Name some of the supplementary pump cooling techniques

A
  1. Open an unused high-pressure hose onto ground2. Open and unused high pressure delivery into the tank filler3. Open Branches regularly4. Connect a Main delivery to the tank filler point5. Disengage the high pressure pump when not required6. Throttle back when high pressure are not requiredSupplementary pump cooling (‘P’ Series Varley) - Provides sufficient flow to prevent high pressure overheating. Switch activated
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16
Q

Describe the use of the pressure relief valve

A
  • Regulates the maximum delivery pressure from the main pump (does not regulate high-pressure pump)- Prevents excessive delivery pressure being transferred to other lines when a hose line is shut off or delivery valves are closed- The relief valve will only bleed off maximum of approximately 200kpa
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17
Q

How do you calculate litres/minute on a HP hose reel?

A

4200kpa = 370 L/min4200 take off 0 = 420 – 50 = 370 L/min3000 kpa = 300 – 50 = 250 L/min2000 kpa = 200 – 50 = 150 L/min1000 kpa = 100 – 50 = 50 L/min

18
Q

what does the Compound gauge indicate?

A
  • Registers positive and negative pressures - Pressure of water entering the pump from a closed supply, - as well as the height of the water being lifted when operating from open water supply- Irrelevant when using tank supply
19
Q

When do you engage the pneumatic monitor?

A

under 200kPa

20
Q

3 types of relay pumping?

A
  1. Tanker2. open circuit3. closed circuit
21
Q

How many litres per min on Darley LDHM 1000 and LDMH 1500 pump?

A

3800 and 5700

22
Q

How do you determine the spacing between appliances when relaying?

A
  1. The pumping capacity of the individual pumps (higher output rating, the greater the distance it can delivery water to the next pump)2. the difference in elevation between the two pumps
23
Q

What are some general rules when relay pumping?

A
  • Strongest Pump at the base- Communication between pump operators- add 10 kPa / meter rise- deduct 10 kPa / meter fall- lines between pumpers should be twinned where possible- gradually increase pressure from 800kPa- release air from system at each pump while charging- base pump operator in charge of relay system
24
Q

Closed Supply faults

A
  1. Failure of water:A. Failure of supply e.g. hose burst, fractured mainRectify - use alternate water supply or replace hoseB. choked strainer (collector or pump)Rectify - disconnect, clear blockage. if this fails, needs to go to workshopC. fall in delivery, negative pressure on compound guage and cavitationRectify - easing back throttle until hydrant can feed the pump again2. Decreased Delivery pressure whilst at workA. burst delivery hose Rectify - replace hoseB. opening of a branch Rectify - ensure sufficient pressure for other branch operators3. Increased Delivery pressure whilst at workA. blockage on delivery side Rectify - disconnect delivery line, clear blockage or replace hoseB. closing down of a branchRectify - ensure pressure relief valve is set to not impact other branch operatorsC. kink in delivery - Rectify - unkink hoseD. Vehicle or fallen debris on hose - Rectify - remove vehicle or debris or replace hose
25
Q

Signs of Over-running supply

A

Term used when a pump is trying to discharge more water compared to water coming in- Compound gauge reading negative (increase negative)- cavitation sign and symptoms- collect inlets going soft or collapsing - discharge pressure and flow reducing- pump revs increasing

26
Q

Rectifying over running supply

A

Quick fix:- reduce pump revs- gate back deliveries- shut off delivery/ies- open tank to pump valveLong term fix:- add additional collectors- use independent standpipes instead of twin heads- fully open standpipes, remedy kinks in collector hose/s- unblock strainers at pump panel collectors

27
Q

Open Supply faults

A

Inability to obtain lift or maintain suction once lift is achievedRecitfy:- Primer- check suction strainer is immersed in water (should be at least 0.5m under)- ensure lift not too great - max lift 7.0m- check if suction hose forming a sharp curve as air pocket can form- check/tighten all suction and coupling joints- close all delivery valves, tank to pump and hose reel valves- primer oil reservoir contains oil

28
Q

label diagram on page 9

A

ImpellerVoluteWater InletGuide VanesDelivery Outlet

29
Q

Factors affecting lift?

A
  1. Creating flow2. Loss due to change in direction of water flow as it enters the suction strainer3. Frictional loss due to resistance of the water passing strainers and suction hose4. Restrictions in the hose (e.g. collapsing line)5. atmospheric pressure6. entry loss - turbulence as the water enters the pump7. Mechanical condition of the pump8. Density of water (e.g. contaminants, chemicals, salt, mud)9. Temperature - higher temp, lower the lift
30
Q

Description of how the Primer works

A

A rotor is set off-centre in a casing fitted with a number of blades that move under centrifugal forcesWhen the rotor is operating, the blades extend and withdraw as the rotor revolves, forming a closed chamber. The volume of the close chamber expands, creating an area of low pressure, more air from the pump /suction hose enters. as the chamber rotates and passes the outlet, the air is exhausted

31
Q

What does the pump pressure gauge indicate?

A

Delivery pressure of water from the main pump

32
Q

What does the High pressure gauge indicate?

A

Delivery of high-pressure pump only

33
Q

What is the operating pressure for both 38mm 230L and 64mm 475L to produce foam solution?

A

1400kPa

34
Q

When should the rams head set up be set for the ground monitor?

A

Always

35
Q

Things to consider for the suction line when draughting?

A

suction line is supported by lines- Deliveries are Open on the other side with TFT branches Open- Run the primer

36
Q

If the light on the relief valve isnt working, what are the indicators/signs that it is still operating?

A
  1. Engine Revs2. water running through the pump
37
Q

What would the pressure need to be set for a 22 story building?

A

P = H x 10P = (22 x 3) x 10P = 66 x 10P = 660660 plus 800 = 1460 kPa

38
Q

Closed Supply Gauge movement faults

A
  1. Gradual increase in delivery pressure and on the compound gauge caused by:- Branches being shut down- Deliver hose line kinked - in water relay, the pump nearest to fire shutting down2. Sudden increase - Weight on delivery hose e.g. vehicle or debris - in water relay, delivery pump has closed branches3. Gradual decrease - Branch being opened - Kinks taken out - Standpipe partially turned off - Weight or kinks in collector lines - in water relay, closing down of deliveries4. Sudden decrease - Burst delivery hose - Burst collector hose - Failure of reticulated water supply - Weight removed off delivery hose lines
39
Q

Open Supply Gauge movement faults

A
  1. Gradual increase in vacuum reading (more negative) and DECREASE in pressure may be caused by:- Dropping water level at source- strainer slowly clogging up- passages becoming chocked (bw pump inlet and impeller)2. Sudden increase - Suction strainer becoming completely blocked- internal lining of suction hose coming loose and causing blockage3. Gradual decrease - Vortex created by the strainer being too near the surface allowing air in- Suction hose joints loose- deterioration of washers4. Sudden decrease in pressure reading may be caused- Burst delivery hose - Weight removed off delivery hose lines - opening a branch / monitor5. Sudden decrease in vacuum reading and decrease in pressure reading may be caused- Suction strainer being completely exposed- pump casing developing a major leak
40
Q

How do you know if the pressure relief valve is set if the lights don’t work?

A

listen to change in revs- hear water running through the system- slight change (drop) in the compound guage

Smooth Operator (29 decks)

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