Shower trap problem!

[GARYF123]

Hi, hope somebody can help. I am installing a Kaskade shower tray (flush with floorboards). It has come with a trap supplied. The trap is 142mm square with a total depth of 79mm from underside of tray to bottom of exit pipe (51mm from underside to centreline of exit pipe). This is obviously sat inbetween the 150mm joists and has to travel 1350mm then 90 degrees then 900mm into soil stack. I am confused regarding the actual trap. From what i can gather from this forum, because i am going into an internal soil stack, the trap needs to have a minimum seal of 75mm? The trap supplied is a compact 80mm depth with adjustable exit, fast flow drainage of up to 40 litres a minute with top access. Is this suitable or do i have to connect a deep trap and cut into my kitchen ceiling and box in to get desired fall using deep trap?
I have recently seen a 40mm bath waste pipe exiting through outside wall directly into a hopper, is this a possible solution?

Many thanks in advance,

Gary.

 

[Llan1observer]

the 75mm trap seal is to counter act the effect of self or induced trap seal loss.

but with a shower or bath there is residual water droplets that slowly work their way down the plug hole refilling the trap if the sael was to be lost...

 

[kirkgas]

a 75mm trap is required if the shower or bath is connected to a soil pipe, a shallow trap is allowed if it connects to a waste water or rainwater pipe