Amendment 0001.docx

Amendment 0001:

The purpose of this amendment is as follows:

1. Extend the solicitation response date to August 10, 2022 @11:59pm

1. Answer the following questions from industry:

Industry Question #1 Looking at the model for the center chamber section, there are 16 holes in the top and bottom flanges that the covers bolt to. We need to know how those covers are bolted to this center section because there may not be enough clearance on the underside of each flange for a nut and washer to clear the body of the center chamber? OR are they going to use threaded rod from the top cover down to the bottom cover with bolts on either end? Plus since we have to test this, we want to know how they want to bolt it together?

NIST Response: NIST left the number and size of bolt holes and the diameter of the bolt circle up to the manufacturer (as well as the size of the O-ring groove). NIST offered (16) 1/2” bolts on a 39” bolt circle as a place holder. Assuming a 1/4” wall thickness for the chamber, this gives 1.25” clearance between the holes and the outer chamber wall, which would accommodate nuts and washers for bolts up to 1.25” diameter. Our preference would be to have the bolt circle sized to allow nuts and washers.

If this is impossible, a second option would be to have tapped holes in the chamber flanges.