I am an instrumentation engineer and I need your help with designing a support structure for a gas-measuring (precision) instrument. The instrument works in an emitter-detector configuration, and measures gas concentration inside a duct. Alignment is key and the detector must always see the emitter. Thermal expansion is the enemy. I am using bellows to create a cushion between the duct and the instrument - the idea is that as the duct heats up, the movement of the duct will minimally interfere with the alignment of the instrument. The emitter and detector each weigh 20lbs. They sit 90" above the ground.
Please refer to the drawing that has 'A', 'B' and 'C' marked. I need your help with the following:
A: the length, width and thickness of the floor plate, and the size of the bolts. Without much knowledge of structures, a 12 x 12 would probably work but that will be the absolute max that can fit at that location. In other words, space is at a premium.
B: size of the square tube. I was advised to use square tube by a mechanical engineer.
C: the purpose of this gusset is to prevent warping or bending of the flat plate that mates with the duct; it's referred to as "process connection" in Drawing 1. I had two designs in mind: one gusset in the middle vs two on the edges, on each side of the plate. I decided to go with the latter as there is more steel to prevent warping. What are your thoughts? I am mounting 50 instruments on 50 ducts so if I can optimize steel usage that will save me money.
PS: Some of you might think this is an overkill for mounting an instrument. This is my third design iteration, and the previous two "minimally invasive" designs failed in giving continuous reliable data. At first, I had mounted the instrument directly to the duct, without any support structures, etc.