I wanted to know if we have any max speed above which i should not be deploying spoilers to slow down the aircraft.
I'm not aware of one, but if there is one, then it is fairly high. Most spoilers on commercial aircraft have a 'Flight Detent' marking on the spoilers, where it is the maximum permitted angle of extension in flight. Spoilers are often used on descents at around FL250 where the speed is still fairly high. For structural safety's sake, the spoilers will be extended slowly and not to a great degree.
Spoilers are also designed to kill lift rather than speed.
If you need to ascend rapidly don't forget to disarm the spoilers! 😉
Its 300KIAS on a 737 (all version of the 737).. not sure about other aircraft though
In most aircraft, the flight spoilers maximum operating speed is the same as the maximum operating speed of the aircraft. What is more important is that you don't use the spoilers below a specified speed and altitude. It depends on the aircraft but min. altitude for spoiler use is 1,000 feet AGL and approach speed +20 kts. Spoilers kill lift and increase stall speed. Spoilers are undesirable at low altitude or while maneuvering(G loads). Aircraft should never be landed with spoilers deployed. Spoilers should only be deployed with thrust levers at Flight Idle, having power and the spoilers is counter productive. Normally you don't have to use spoilers very much. If you plan your descent correctly, you should need little use of spoilers. Spoilers are for times when you need to descend more rapidly than normal and maintain a reduced airspeed. 🙂
In the 737 at FL300, you can descend at 300 KIAS, Flight idle, at a rate of 4000 FPM. !0,000 feet, 250 KIAS, Flight Idle, 2000-2500 FPM. Those descent rates are good for most situations.