Hi all! Been looking for a while for replacement o-rings for the spindle of the pre heater burner belonging to my Dae rim annby 105 stove. It’s the one in my profile pic. The spindle is leaking air so the tank won’t hold pressure. The rings are deformed with age so i am not sure what sizes I would need. Does anyone know what the sizes needed are, or should be? Also what is the shore value of the viton that i should use? I will (try to) include a picture of the spindle and a little drawing with some measurements The whole thing is about 21mm long. On the right are the inner brass diameters on the left the heights of the brass recesses. The outer diameters of the rings are 4,7mm and 6mm as they are. Thanks for any advice! Greets Job
Hi @Jobmeel , O rings are designed to be either compressed, or expanded, a small percentage to obtain a seal. You'll need to mesure the diameter of whichever surface they seal against and factor this in. Then try to find the nearest possible option in Viton. It's unlikely you'll have much choice with different grades of shore hardness. Unless somebody knows the exact original dimensions of course...
Hi, thanks for your reply. I’ve included a picture of the opening it fits in. the top o ring appears to rest against a tapered surface all the way down the hole. I have no means of measuring down there. The bottom o rings cord diameter is slightly oval and the ring measures 6mm in full width. Since it’s leaking i’m guessing the opening it’s in is also about 6mm. How much bigger would the ring have to be to fit well?
@Jobmeel It might have to be trial and error then! With Viton O rings, I always aim between 8% and 15% to give the required compression, although sometimes that's just not possible if the components were made before standards were introduced!
@Jobmeel For the larger of two o-rings, the missing diameter in my opinion is that of the tube that it slides in to. It's function is to prevent fuel / vapour leaking out towards the control knob. You need something that will press against the inner 3.2 mm that you have measured and the wall of the tube it slides in. It also needs to be pretty close to 1.9 mm so that the adjusting the spindle controls the flow without any noticeable backlash. If you consult O-ring manufacturer's information there is a wealth of information about how they work. See section 3 of the example that I've linked for the principles of how they work and section 15 that starts with the sizes commonly used in different countries. The smaller one looks like it seals against a conical counterbore at the end of the recess the device screws in to and therefore has to protrude far enough that it pushes against the end of the recess before the metal part that it sits in does. Regards John
If you can find something the size you want, go for the harder option, if you can't get the ideal, the softer will have more 'give'... As mentioned above, you may be lucky and the stove was designed to use O-rings of a standard size still produced. But you may not be lucky!
