Method and apparatus for stabilizing the thickness of an optical channel for extended pressure environments

Patent metadata

Field	Value
Publication number	US-9541492-B2
Application number	US-201514727754-A
Country	US
Kind code	B2
Filing date	Jun 1, 2015
Priority date	May 30, 2014
Publication date	Jan 10, 2017
Grant date	Jan 10, 2017

Abstract

A high pressure optical flow cell system suitable for use in a real time optical particle monitoring system. The system is modular, with at least two housings joined together with removable mechanical attachment devices. Inlet and outlet passageways introduce and remove high pressure fluid into a flow cavity located between adjacent housing faces. An o-ring or other compliant member seal is provided between the faces to prevent leaks of the high pressure fluid. At least one optical window is provided with a substantially planar face flush with the flow cavity surface. An optical assembly maintains the face of the optical window flush with the flow cavity surface over a wide range of temperatures and pressures. A system and method for maintaining the face of the optical window flush with the flow cavity surface over a wide range of temperatures and pressures.

First claim

What is claimed as new and desired to be protected by Letters Patent of the United States is:

1. A high pressure cell for viewing high pressure fluid passing through the cell, comprising:
a first housing member and a second housing member;
a spacer member sandwiched between substantially planar surfaces of the first housing member and the second housing member, the spacer member having a thickness less than the first and second housing members,
the spacer member having a hole therethrough with an edge of the hole defining a flow cavity between the first housing member and the second housing member;
each of the first housing member and the second housing member having a groove for a gasket on a surface of the housing member that faces the spacer member, each groove surrounding and being larger than the hole through the spacer member;
an inlet passage formed in either the first housing member or the second housing member extending from an outer face of the first or second housing member to the flow cavity;
an outlet passage formed in either the first housing member or the second housing member and extending from an outer face of the first or second housing member to the flow cavity;
an optical window in a mounting hole of the first housing member positioned with a surface of the optical window exposed to the flow cavity,
wherein the at least one window has first portion at a first end with a substantially constant smaller cross sectional area, a second portion at a second end with a substantially constant larger cross sectional area, and a shoulder between the first and second portions, wherein the at least one window is positioned in the mounting hole with the first end facing the flow cavity;
a compliant gasket positioned around the first portion of the window between the shoulder of the window and a corresponding first shoulder surface in the mounting hole; and
an externally threaded retaining member having a central opening configured to let light pass through the retaining member along a main axis,
the externally threaded retaining member being positioned in a threaded portion of the mounting hole, such that tightening the retaining member compresses the gasket against the first shoulder of the mounting hole, creating a static seal against fluid leaking past the window and positioning the window with an end face at the surface of the flow cavity.

2. The high pressure cell according to claim 1 , further comprising:
another optical window in a mounting hole of the second housing member positioned with a surface of the optical window exposed to the flow cavity, the optical windows being aligned on opposite sides of the flow cavity to transmit and receive light into and from the cavity, respectively.

3. The high pressure cell according to claim 2 , wherein each window has a planar end surface that is flush with the surface of the adjacent housing member that faces the flow cavity.

4. The high pressure cell according to claim 1 , wherein the inlet passageway has an opening to the flow cavity at an upstream location relative to the window, and the outlet passageway has an opening to the flow cavity at a downstream location relative to the window.

5. The high pressure cell according to claim 1 , further comprising:
mechanical attachment elements arranged to hold the first housing member, the spacer member, and the second housing member together when high pressure fluid passes through the cell.

6. The high pressure cell according to claim 5 , wherein the mechanical attachment elements include threaded screws or bolts positioned in corresponding mating holes that extend entirely through the first housing member and at least partially through the second housing member.

7. The high pressure cell according to claim 6 , wherein the number and size of threaded screws and bolts is determined based on the yield strength of the housing members and screws or bolts and the expected pressure of the fluid passing through the cell.

8. The high pressure cell according to claim 1 , further comprising:
a gasket positioned in each groove in the first and second housing members to form a static seal.

9. The high pressure cell according to claim 8 , wherein the gasket is an o-ring.

10. The high pressure cell according to claim 8 , wherein the grooves are elongated with a length greater than their width, or wherein the gasket and grooves have an oval shape.

11. The high pressure cell according to claim 1 , further comprising:
a light directing module attached to either the first housing member or the second housing member and having at least one reflector,
wherein an optical path extends from the flow cavity to a reflector in the light directing module to direct light out of the cell.

12. The high pressure cell according to claim 11 , wherein the at least one reflector is a dove prism positioned to receive light from the flow cavity after the light has passed through the flow cavity, and to direct the received light through openings in the first housing member and the second housing member to exit the cell, and the cell further comprising:
a housing configured for mechanical attachment to either the first or second housing member to hold the dove prism in position.

13. The high pressure cell according to claim 12 , wherein each of the first and the second housing members and the light directing module have a plurality of holes extending therethrough aligned with each other to receive mounting bolts or other connectors.

14. The high pressure cell according to claim 1 , further comprising:
a flat washer and a flat spacer positioned in the mounting hole, each of the washer and the spacer having a through hole that is smaller than the cross sectional dimension of the first portion of the window,
the washer being positioned in the mounting hole between the window and the spacer, and the spacer being positioned in the mounting hole between the washer and the threaded retaining member,
the washer being thinner and formed of a more compliant material than the spacer, and the spacer being thinner and formed of a more compliant material than the threaded retaining member,
wherein tightening the retaining member compresses the washer and spacer against a second shoulder of the mounting hole, and compresses the gasket against the first shoulder of the mounting hole, creating a static seal and positioning the window with an end face at the surface of the flow cavity.

15. A method for illuminating high pressure flowing fluid in a high pressure cell, comprising:
providing the high pressure cell, including
a first housing member and a second housing member,
a spacer member held tightly between substantially planar surfaces of the first housing member and the second housing member, the spacer member having a thickness less than the first and second housing members,
the spacer member having a hole therethrough with an edge of the hole defining a flow cavity between the first housing member and the second housing member,
each of the first housing member and the second housing member having a groove for a gasket on a surface of the housing member that faces the spacer member, each groove surrounding and being larger than the hole through the spacer member,
an inlet passage formed in either the first housing member or the second housing member extending from an outer face of the first or second housing member to the flow cavity,
an outlet passage formed in either the first housing member or the second housing member and extending from an outer face of the first or second housing member to the flow cavity,
an optical window in a mou

Assignees

• Us Navy

Inventors

• Howard Paul L
• Tucker John E
• Reintjes John F

Classifications

• G01N21/0317

  High pressure cuvettes; (G01N21/0332 - G01N21/15 take precedence) · CPC title

• G01N33/2858

  Metal particles · CPC title

• G01N33/2888

  Lubricating oil characteristics, e.g. deterioration (lubricating properties G01N33/30) · CPC title

• G01N21/11

  Filling or emptying of cuvettes · CPC title

• G01N2021/0389

  Windows · CPC title