7.9 Flashcards
What are pipes and hoses dimensions determined by?
External diameter and wall thickness.
What pressures are high pressure lines?
Over 1500 psi (105 bar)
What pressure are medium pressure lines?
Under 1500 psi
What are low pressure lines?
Suction and return lines.
What are medium and low pressure lines preferably made of?
Aluminium for weight saving.
Where must steel lines be used?
Engine areas, areas in danger of fire and undercarriage where stones can hit.
What can titanium lines be used for?
Flexible metal pipes instead of hoses.
How are pipes and hoses proof tested?
With 1 1/2 it’s working pressure of compressed air and capping one end.
What are the 2 most common support clamps for pipes?
Rubber cushioned and plain.
What support clamps are used for pipes in areas subject to contamination?
Cushioned clamps utilising Teflon.
What is a bonded clamp used for on pipes?
Secure metal, fuel, oil or hydraulic lines.
What principle achieve the seal for flareless tube fittings?
Ball bush principle.
What are the 2 flareless fittings?
MS and Harrison.
How is a Harrison fitting secured?
Swaged in the sleeve from the inside.
What are the 2 types of flare?
Single and double flare.
What advantage do flared fittings have in engine areas?
They are vibration-resistant.
What is the standard flare angle?
37 degrees.
How are single flares formed?
Impact type or roll type.
What colour are flared AN fittings?
Black are blue.
What colour are AC flared fittings?
Grey or yellow.
What angle are AC flare fittings?
35 degrees.
Are AN fittings coarser or finer than AC fittings?
Coarser.
What size aluminium tubing can be double flared?
Outside diameter 3/8 in or smaller.
What is a disadvantage of a permaswage fitting?
It cannot be separated. Problematic on disassembly.
On pipes and hoses, what is the maximum damage for sharp bottomed surface defects?
5%
On pipes and hoses, what is the maximum damage for round bottomed surface defects?
10%
What can the length must not be more than for a trace of impact damage on pipes and hoses?
5mm
How much slack must there be on hoses between fittings?
5-8%
By how much do hoses reduce in length when under pressure and expand?
2-4%
Why are twisted hoses bad?
Shortened life and end fittings can loosen off.
What are flexible hoses for?
Connect stationary moving parts and in areas of high vibration.
What pressure are high pressure hoses?
3000+ psi
What pressure are medium pressure hoses?
Up to 3000 psi
What pressure are low pressure hoses?
Up to 600 psi
What is psi?
Pounds per square inch.
What colour are lay lines on hoses?
Red, yellow or white stripes.
Other than containing hose information, what can they indicate?
If a hose is twisted.
Can you re-use hose end fittings?
Yes, must be thoroughly inspected.
How often must a hose be supported?
At least every 24 inches.
What protective sleeves can be used on hoses?
Heat shrink, nylon spiral wrap, Teflon.
What acts as a witness mark when a hydraulic fittings has been torqued?
A red paint mark 2-4mm wide.
