Gas parameter sensing apparatus and method

Apparatus for detecting the direction of flow of a gas within an enclosed, elongated line, said apparatus comprising:

• a) a hollow member having first and second, mutually isolated, internal compartments;
• b) first and second passages through which said first and second compartments, respectively, communicate with the exterior of said member;
• c) a differential pressure detecting device for indicating which of two pressures communicated to said device is higher than the other;
• and
• d) third and fourth passages through which the pressures within said first and second compartments, respectively, are communicated to said device.

The method of sensing one or more parameters of a gas flowing through an elongated, enclosed line, said method comprising:

• a) forming an opening in a wall of said line;
• b) attaching to said line in covering relation to said opening a length of piping having a linear axis extending radially of said line, said piping comprising a plurality of releasably connected sections including a first section containing an isolation ball valve and a second section containing a packing gland having a first passageway of first diameter, said piping between said second section and said line having a second passageway of not less than a second diameter, larger than said first diameter, said packing gland being spaced along said axis by a first distance from said ball valve on the opposite side of said ball valve from said line;
• c) disconnecting said second section from said piping;
• d) axially advancing through said passageway the distal end of a tubular member having an outer diameter substantially equal to said first diameter;
• e) attaching to said tubular member an element extending radially outwardly from the plane of said outer diameter to provide a cross dimension greater than said first diameter and less than said second diameter, to form an elongated wand comprising at least said tubular member, said element and a sensing portion, said element being on the same side of said second piping section as said distal end of said tubular member, whereby said element prevents axially retracting movement of said wand through said passageway past said element;
• f) connecting said second section to said piping;
• g) opening said ball valve;
• h) axially advancing said wand through said piping until said sensing portion is positioned within said line;
• i) sensing said at least one parameter;
• j) axially retracting said wand through said piping until said distal end is positioned between said ball valve and said first passageway;
• and
• k) closing said ball valve.

The method of shortening the axial length of an elongated wand having a probe carrying sensing elements for generating electrical signals commensurate with mass flow of a gas to which said elements are exposed, and a hollow tube having a distal end connected to said probe and a proximal end connected to a housing containing a terminal block for connection of wires extending from said elements through said hollow tube and into said housing through an opening communicating with the interior of said tube, said method comprising:

• a) affixing to said housing a threaded fitting having a through passageway communicating with said opening;
• b) slidably inserting on said proximal end of said tube a nut having threads matable with said threaded fitting;
• c) affixing to said proximal end of said tube a ferrule;
• d) passing said wires from said tube through said threaded fitting and opening, into said housing and connecting said wires to said terminal block;
• e) threadedly engaging said nut with said threaded fitting to urge said ferrule into engagement with said threaded fitting;
• and thereafter:
• f) disconnecting said wires from said terminal block;
• g) disconnecting said nut from said threaded fitting, removing said ferrule from engagement with said threaded fitting and pulling said wires out of said housing through said opening and threaded fitting;
• h) severing a portion of said tube to form a new proximal end;
• i) pulling said severed portion and its attached ferrule over the ends of said wires while leaving said nut slidingly engaged on said tube;
• j) affixing a new ferrule to said new proximal end;
• k) passing said wires from said tube through said threaded fitting and opening, into said housing and reconnecting said wires to said terminal block;
• and
• l) threadedly engaging said nut with said threaded fitting to urge said new ferrule into engagement with said threaded fitting.