Questions regarding P-tube and trip wire

[foodprocessor1]

Defining the P-tube and the trip plate or trip wire.

I am about to make my first small-scale rocket mass heater and want to include Peter's new features but cannot conceptualize these features clearly.

For a batch horizontal feed. The box can be long (up to 2 feet) but must narrow towards the opening leading to the heat riser? This narrowing must be about 7 percent smaller cross sectional area then the cross sectional area of the heat riser?

The trip plate will be located near the end of the feed tube and at the 12:00 position in the tunnel sticking down (facing towards the center of the earth) less than 5 percent the diameter of the feed tube at that point?

Is the pre-heated fresh air supply piped through the feed tunnel (and positioned at the 10:00 position) essentially the P-tube?

Any help with the above definitions will help me to include these features in my next stove.

[peterberg]

Hello foodprocessor1, welcome to the boards. I'll try to answer your questions though I'm not entirely sure what you mean.

Feb 20, 2013 16:46:15 GMT -8 foodprocessor1 said:

For a batch horizontal feed. The box can be long (up to 2 feet) but must narrow towards the opening leading to the heat riser? This narrowing must be about 7 percent smaller cross sectional area then the cross sectional area of the heat riser?

My model of the batch box rocket stove isn't narrowing towards the heat riser, at all. There's no need for that. The opening to the heat riser, provisionally called "the port" is about 70% of the heat riser c.s.a., assuming this riser is round.

Feb 20, 2013 16:46:15 GMT -8 foodprocessor1 said:

The trip plate will be located near the end of the feed tube and at the 12:00 position in the tunnel sticking down (facing towards the center of the earth) less than 5 percent the diameter of the feed tube at that point?

In my experimental version of the batch box there isn't a trip wire and no feed tube either. Probably you are mixed up with my earlier experiments regarding Small scale development.

Feb 20, 2013 16:46:15 GMT -8 foodprocessor1 said:

Is the pre-heated fresh air supply piped through the feed tunnel (and positioned at the 10:00 position) essentially the P-tube

This question isn't clear at all, I'd suggest you start to use the proper names for the different parts. The Ianto Evans rocket mass heater is quite different from the batch box rocket, by the way.

May I suggest you read the following threads, preferably in its entirety?

Adventures with a horizontal feed

Small scale development