DP backed up does work. Its not ideal but in competant hands it works and they supress then cool the fire. Suppression systems are the best though. Manually operated if possible, if you wait for the automatic links to break the fire will have spread, possibly to unprotected areas outside the nozzle spread or on appliances incorrectly protected.
Ask the restaurant staff at BHS Wigan. Breakfast was a bit disturbed yesterday with a faulty 3 basket fryer fire. They pulled the MPS and were cooking by lunch.
By rights if suppression systems were fitted and correctly maintained the risk of fire spread is massively reduced. But its always a cost game.
FM's run the world these days and they want to keep their contracts so keep costs to a minimum. As long as they've got the cert and box ticked all is well.
As for fire blankets, why are they sat next to fryers in commercial kitchens if they are not suitable for use? Training or lack of, incorrect advice from fire company engineers/technicians/whatever they're called this week, incorrect manufacturer marketing, profit before safety etc etc.
Try using one on a 18x25" 600.F fryer spitting burning fat out, yet there they sit, next to the fryers. I've stacks of photo's of blankets sat above fryers, sockets/switches sat above fryers etc yet they (the premises) all get pass certs for fire risk assessments.
To say i'm embarrassed with our industry is putting it mildly. The complete lack of competent training and legistive blackmail to sell more products merely for commission and profit its pure hipocrosy.