received by the International Bureau on 19 April 2018 (19.04.2018)

What is claimed is:

1. A flow meter assembly having a longitudinal axis, the flow meter assembly comprising: an upstream member comprising a first end, a second end, and a fluid passageway extending between the first and second ends;

a downstream member comprising a first end and a second end; and

a first throat member comprising a first end, a second end, and a fluid passageway extending between the first and second ends, wherein the fluid passageway of the first throat member has a minimum diameter that is less than a minimum diameter of the fluid passageway of the upstream member;

wherein the first throat member is configured to releasably couple to the upstream member and the downstream member.

2. The flow meter assembly of claim 1, wherein the first end of the first throat member is configured to releasably couple with the second end of the upstream member and the second end of the first throat member is configured to releasably couple with the second end of the downstream member.

3. The flow meter assembly of claim 1, wherein, when the first throat member is releasably coupled to the upstream member and the downstream member, the flow meter assembly comprises a first beta ratio comprising the minimum diameter of the fluid passageway of the first throat member divided by a maximum diameter of the fluid passageway of the upstream member.

4. The flow meter assembly of claim 3, further comprising a second throat member configured to releasably couple to the upstream member and downstream member and comprising a first end, a second end, and a fluid passageway extending between the first and second ends, wherein the fluid passageway of the second throat member has a minimum diameter that is less than the minimum diameter of the fluid passageway of the first throat member.

5. The flow meter assembly of claim 4, wherein, when the second throat member is releasably coupled to the upstream member and the downstream member, the flow meter assembly comprises a second beta ratio comprising the minimum diameter of the fluid passageway of the second throat member divided by the maximum diameter of the fluid passageway of the upstream member, and wherein the second beta ratio is different from the first beta ratio.

6. The flow meter assembly of claim 1, wherein:

the second end of the upstream member comprises an angled engagement surface and the first end of the first throat member comprises an angled engagement surface; and

engagement between the engagement surface of the upstream member with the engagement surface of the first throat member is configured to axially align the upstream member with the first throat member.

7. The flow meter assembly of claim 6, wherein:

the angled engagement surfaces of the upstream member and the first throat member each comprise conical engagement surfaces; and

the engagement surface of the first throat member is configured to be inserted into the second end of the upstream member.

8. The flow meter assembly of claim 1, wherein:

the first end of the first throat member comprises an annular flange;

the second end of the upstream member comprises an annular flange; and

the flow meter assembly further comprises a plurality of threaded fasteners extending between the flanges of the upstream member and the first throat member to couple the upstream member with the throat member.

9. A flow meter assembly having a longitudinal axis, the flow meter assembly, comprising: an upstream member comprising a first end, a second end, and a fluid passageway extending between the first and second ends;

a downstream member comprising a first end and a second end; and

a throat member comprising a first end, a second end, and a fluid passageway extending between the first and second ends, wherein the throat member is configured to provide a restriction in a fluid flow passing through the flow meter assembly;

wherein the throat member is removably coupled to the upstream member and the downstream member.

10. The flow meter assembly of claim 9, wherein the flow meter assembly comprises a first beta ratio comprising a minimum diameter of the fluid passageway of the throat member divided by a maximum diameter of the fluid passageway of the upstream member.

1 1. The flow meter assembly of claim 9, wherein:

the first end of the throat member comprises an annular flange;

the second end of the upstream member comprises an annular flange; and

the flow meter assembly further comprises a plurality of threaded fasteners extending between the flanges of the upstream member and the throat member to couple the upstream member with the throat member.

12. The flow meter assembly of claim 9, wherein:

the first end of the throat member comprises an alignment pin; and

the second end of the upstream member comprises an alignment receptacle configured to receive the alignment pin of the throat member to axially align the upstream member with the throat member.

13. The flow meter assembly of claim 9, wherein:

the second end of the upstream member comprises an engagement surface and the first end of the throat member comprises an engagement surface configured to engage the engagement surface of the upstream member; and

the engagement surfaces of the upstream member and the throat member each comprise an annular groove configured to receive an annular seal to seal an interface between the upstream member and the throat member.

14. The flow meter assembly of claim 9, wherein:

the second end of the upstream member comprises an engagement surface and the first end of the throat member comprises an engagement surface configured to engage the engagement surface of the upstream member; and

the flow meter assembly further comprises a gasket disposed axially between the upstream member and the throat member to seal an interface between the upstream member and the throat member.

15. The flow meter assembly of claim 9, wherein the fluid passageway of the first throat member has a minimum diameter that is less than a minimum diameter of the fluid passageway of the upstream member.

16. A method of measuring a rate of fluid flow using a flow meter, comprising:

coupling a first throat member to an upstream member of a flow meter and a downstream member of a flow meter to provide the flow meter with a first beta ratio;

measuring a first flow rate of a fluid flow through the flow meter;

removing the first throat member from the flow meter; and

coupling a second throat member to the upstream member of the flow meter and the downstream member of the flow meter to provide the flow meter with a second beta ratio that is different than the first beta ratio.

17. The method of claim 16, further comprising:

measuring a second flow rate of the fluid flow through the flow meter after the second throat member is coupled to the upstream member of the flow meter;

wherein the first flow rate is within a first flow rate range and the second flow rate is within a second flow rate range that is different from the first flow rate range.

18. The method of claim 16, further comprising engaging an angled engagement surface of the first throat member with an angled engagement surface of the upstream member to axially align the upstream member with the first throat member.

19. The method of claim 16, further comprising extending a threaded fastener through a flange of the upstream member and a flange of the first throat member to releasably couple the upstream member with first throat member.

20. The method of claim 16, further comprising extending an alignment pin of the first throat member into an alignment aperture of the upstream member to axially align the upstream member with the first throat member.