Fabricating the CNG filter bracket
(Click any pic for a enlarged view)

Even though NFPA 52 does not require a high pressure CNG filter, I decided to add one. I have seen these filters in reference articles on various CNG forums and in reference information for various CNG vehicles. I also figured an extra filter can do no harm and add an extra layer of protection.

This is a Parker-Hannifin compact CNG filter, model FFC-112 SAE-10. I picked up 2 of these in an Ebay auction at $51.00 apiece. The guy had 10 to sell. I should have bought more.

The filter is going to need a firm anchoring point and to start, I am going to use a piece of 1/4"x2" bar as the base of the bracket.

Fortunately the existing tank straps have two vertical bosses that provide two perfect points to bolt an anchoring bar to.

With the bar in place I needed to determine the filter height. So I hand screwed the check valve into the CNG tank and bent the first piece of 1/4" pipe.

Once the pipe was installed and the filter set. I clamped a transitional piece of bar at the correct height.

The transitional piece was marked and clamped up for welding.

Both sides of the bar were TIG welded.

Using a piece of cardboard I cut a template to complete the transition.

The template is transferred to a piece of 1/4" plate. Then I let the metal cutting band saw do all the work. I wish I had a more trick way of doing this. It is what it is.

After some cutting and grinding, the transitional piece is done.

It is now clamped up and ready for welding.

For cosmetic reasons I TIG welded the outside.

Then "DC" stick welded the inside.

With the welding complete, I then transferred the filter mount holes to the bracket using a masking tape template.

The mounting holes are drilled and chamfered.

and the filter is test bolted for fit and clearance.

After a trip to the sand blasting booth, the bracket is ready for finishing.

4 heavy coats of Rustoleum will provide the necessary weather protection. The bracket is now complete and ready for final install.

Before the finished bracket and filter can be attached, a bulkhead fitting needs to be installed. This will allow supply gas to fill the CNG tanks. Here the hole is drilled and silicon rubber is applied in both sides of the bed floor.

Here a crescent wrench is wedged against the tank mount so the bulkhead nut can be tightened from the bottom.

a little lacquer thinner will clean up the excess silicon rubber.

Once the bulkhead fitting is in place a piece of pipe is bent to connect the fitting to the filter. Thermal expansion and contraction will weaken and compromise the pipe and fittings. The loop serves as a shock absorber.

Here the bent pipe is screwed onto the bulkhead fitting and a measurement is taken for the flare nut.

The pipe is cut an the flair applied. It is now ready for assembly.

Here is a view of the pipes, filter and bracket assembled.