Is the CRDi System's Mechanical Pressure Control Valve Limited to 10 Uses?

[monty37]

i recently saw the CRDi system ,its working and its performance test.Now there is a particular
mechanical pressure control valve being used in the rail to prevent excess pressure,this valve works each time pressure goes beyond the limit and brings it down,but it is said that this happens only 10 times after which the whole thing has to be changed.but why is it 10 times and does this change from vehicle to vehicle?

 

[Mech_Engineer]

Diesel direct injection systems operate at very high pressures, and the valve is only there as a last resort in the event of a rare unexpected overpressure of the fuel system. It shouldn't need to operate many times, because it's protectting against a rare event. How many times this kind of a safety feature can operate will depend on the vehicle, on some vehicles it could be more of a burst disc and only operate once before needing replacement.

 

[monty37]

how does this mechanical valve differ in function from the M-PROP ,which is also used
for pressure control?

 

[brewnog]

Never heard of an M-PROP, please elaborate.

 

[monty37]

there is a part called m-prop ,i don't know if it is generally called m-prop(it's bosch crdi).
the CRDi systems that used the m-prop fixed to the pump,they don't use the pressure control valve in the rail.

 

[zente]

I used to work on high and low pressure safety valves for the oil and gas industry and the reason for the limited usage of the safety valve is due to its high pressure and service ( fuel ). The simplest way I can think of it is like a water jet used for cutting metal etc. When the high pressure is released, it is vented past the seat ( sealing surfaces ) and valve, and in the fraction of a second it requires to open and when pressure drops, to close back off you you will get a cutting action of the fluid at such high pressure. The seating surfaces must maintain a gas tight seal and any minor inpurfection will cause a leak and any leak will quickly get worse at high pressure and so to avoid problems they put a practical limit on number of openings to mitigate possible major problems and related lawsuits. Also in general the high pressure fuel valve we worked on had metal to metal seating surfaces and the oil industry was require to replace them or have them service twice a year reguardless of times they opened as a minimum standard. I hope this helps.

zente

 

[monty37]

that very well explains the purpose of the valve,but its the terminology that is unclear,
the m-prop and the pressure control valve.

 

[brewnog]

I've been dealing with fuel injection equipment for years now, never heard of an M-prop. If you want answers perhaps you could elaborate; what's the context of this valve, where is it situated, what do other manufacturers call it etc. You must know more about it than its name.

 

[zente]

I found a very good article on the CRD systems and explains about the M-Prop or magnetic proportional valve and how it is used in a Closed loop system ...

http://findarticles.com/p/articles/mi_qa3828/is_201005/ai_n54366060/

Hope this helps

Zente

 

[brewnog]

There you go, it's the PWM valve!

Good article, thanks.

 

[monty37]

thanks that did help,so its a magnetic proportional valve