Heat fusion pipe fitting system

Abstract: A pipe fitting system in which an element in or on the body of the pipe fitting may be interrogated to ascertain information such as time and/or current required to effect fusion. The element, on being interrogated, automatically transmits the required information. In the body of the pipe fitting is a recess 9 in to which is snap fitted an information containing element 11 held in position by lugs 9a and 9b. A fusion control unit 20 is provided which is supplied with power via lead 21. The unit 20 is equipped with a transmitter receiver for interrogating the information containing element 11. The transmitter receiver may be incorporated in the control unit 20 and suitable antennae may be incorporated in the box 22.

Description: This invention relates to a heat fusion pipe fitting system for thermoplastic pipes. It is known to use thermoplastic heat fusion pipe fittings to join thermoplastic pipe members and also to provide branch pipes by using fittings known as saddles. Such fittings have in the past been provided with electrical heating elements embedded in the body of the fitting in close proximity to the surface of the fitting to enable the fitting to be joined to the pipe by passing a current through the heating element which heats the surface of the fitting and the adjacent surface of the pipe and causes heat fusion of the two. It is necessary for the operator to know how much current should be passed through the fitting and for what is period of time in order to attain optimum jointing. In U.S. Specification 4642154 (Fischer) a system is described in which the type and resistance of the heating element are determined in advance by measurement of the wire impedance which indicates both type and ohmic resistance. Welding time is then selected from a predetermined directrix depending on the resistance and the directrix itself is chosen on a basis of type by the impedance measurement. A more sophisticated system is described in U.S. Patent Specification 4486650 (Fusion Plastics Limited) in which a resistor with a value chosen in accordance with the power to be supplied to the coil is connected between main and auxilliary terminals so that the measurement of the resistance of the coil is not necessary, all that is necessary is to measure the resistance of the addition resistor which provides the required information. In the present Applicant's U.S. Patent 4571488 (A.V. Reeves assigned to E.I. Du Pont De Nemours & Company) a system is described in which the body of the fusion pipe fitting is provided with a shaped coding tag containing holes or slots arranged in a predetermined sequence for use with a light detecting control system. Signal generating means are used which may for instance be incorporated in or extend from a fusion control unit, which pass an electromagnetic radiation signal through the shaped coding tag and the holes or slots are arranged to pass or stop the electromagnetic radiation in a predetermined sequence for use with a light detecting control system. This system although satisfactory is limited in the amount of information that can be conveyed. An object of this invention is to provide a sophisticated pipe fitting system in which an element incorporated in or placed upon the body portion of the pipe fitting may be interrogated by an electromagnetic signal so as to cause the element to transmit the required information. More specifically in accordance with the present invention there is provided a thermoplastic heat fusion pipe fitting having a body portion adapted to fit over a pipe and to be fused thereto by means of an electrical heating element incorporated in the body portion, and an information containing element being incorporated in or on the body portion, characterised in that said element is arranged to transmit signals revealing said information on being interrogated by an electromagnetic signal from an external source. The electromagnetic signal is preferably a radio frequency signal and said information containing element is preferably a passive element which only emits the information containing signals on interrogation by the RF signal. Preferably the information containing element itself contains no power source but relies for power on receipt and conversion of the RF signal. Alternatively, the information containing element may be self powered, the power only being switched on when initiated by the RF signal, the element then transmitting the required information. Information in the information containing element is preferably contained in the form of a micro-chip and may be quite extensive in terms of memory for instance up to 54 bit pre-programmed memory. The interrogating RF signal may be produced by a fusion control unit which may also contain a decoder to decode the signal transmitted by the information containing element in addition to the other controls normally in a fusion control unit. The information containing element may contain information selected from, for example:- time and/or current and/or voltage required to effect fusion; type of fusion pipe fitting; manufacturing details e.g. date of manufacture and source; material from which the pipe fitting is manufactured; type of pipe fitting (e.g. sleeve or saddle); compensation characteristic for temperature extremes; and special instructions for post fusion treatment. The information containing element may be moulded in to the body portion of the pipe fitting or it may be in the form of a slug or pellet which is snap fitted in to an appropriate cavity in the wall of the fitting. The transmitter for interrogating the information containing element may be in a lead coming from the fusion control unit or may be in a small box at the end of a lead coming from the fusion control unit or it may be in the fusion control unit itself. The location will depend upon the power of the transmitter. In the accompanying drawings:- Figure 1 shows one application of the invention to a sleeve type heat fusion pipe fitting system; Figure 2 shows the sleeve type fitting with the information containing element incorporated in it; and Figure 3 is a schematic block diagram showing the essential elements of the system which are incorporated in the fusion control unit. In Figure 1 is shown a tubular or sleeve type pipe fitting adapted to join two pipes end to end. The fitting 10 is provided with terminals 12 and 13 which are connected to a heater wire 14 (see Figure 2) in conventional manner. In the body of the pipe fitting is a recess 9 in to which is snap fitted an information containing element 11 held in position by lugs 9a and 9b. Alternatively the information containing element 11 could be moulded in the wall of the pipe fitting. A fusion control unit 20 is provided which is supplied with power via lead 21. The unit 20 is equipped with a transmitter receiver for interrogating the information containing element 11. The transmitter receiver may be incorporated in the control unit 20 and suitable antennae may be incorporated in the box 22. Alternatively the whole of the transmitter receiver equipment may be in box 22 or may be incorporated in the lead 24 or 25. Power is supplied to the terminals 12 and 13 via leads 24 and 25 again in conventional manner. The information containing element 11 may contain information as described above but it is particularly preferred that it should contain information as to the voltage and time or current and time necessary for efficient jointing of pipes using the fitting. It may contain much other information as mentioned above. The fusion control unit 20 may, as mentioned above contain the transmitter receiver 26 (Figure 3) and may supply the interrogating signal in the form of an RF signal via lead 23 to antennae 22 which both transmit the RF and receive the transmission from the information containing element 11. In the control unit 20 may also be a decoder 27 which separates out the information relating to the time and current required and supplies that information to a fusion current control and timer unit 28 supplied by power source 29. The decoder may also supply other information to a recorder 30 so that in the recorder may be collected information relating to each of the fusion pipe fittings fitted in the particular day. The recorder may record all the necessary information not only that derived from the information containing element 11 but also any additional information which may be fed in to the recorder by the operator such as the location of fitting, timer fitting, operator's name etc. At the end of the day the recorder, or the record it contains, may be removed from the unit 20 and its contents put on to a computer or other form of permanent record. Although the illustrated pipe fitting is a sleeve the system may equally well be applied to an elbow or saddle type fitting which are available and manufactered by Du Pont (UK) Limited. Instead of employing a separate antenna, the heater coil may itself be used as the antenna. The circuit may be arranged so that once fusion is complete the information containing element may be disconnected or isolated so that the fitting cannot be re-fused. Re-fusing of units can be dangerous in that it may lead to overheating, so it is usual to allow at most one re-fuse after a predetermined time has elapsed and only under controlled circumstances. This action may also be controlled by the element 11 e.g. the element 11 may inhibit operation (i.e. a second fusion) until the joint has cooled to a predetermined temperature.

Claims: A thermoplastic heat fusion pipe fitting (10) having a body portion adapted to fit over a pipe and to be fused thereto by means of an electrical heating element (14) incorporated in the body portion, and an information containing element (11) being incorporated in or on the body portion, characterised in that said element (11) is arranged to transmit signals revealing said information on being interrogated by an electromagnetic signal from an external source. A thermoplastic heat fusion pipe fitting according to claim 1 characterised in that said electromagnetic signal is a radio frequency signal. A thermoplastic heat fusion pipe fitting according to claim 1 or 2 and characterised in that said information containing element (11) is a passive element which only emits said signal on interrogation and which does not include its own power source. A thermoplastic heat fusion pipe fitting according to claim 3 characterised in that the power for causing said element to emit a signal is derived from receipt and conversion of the external radio frequency signal. A thermoplastic heat fusion pipe fitting according to claim 1 or 2 characterised in that the information containing element (11) is self-powered and transmits a signal containing information on the power being initiated by the RF signal, the power being derived from a battery contained in the element. A thermoplastic heat fusion pipe fitting according to any preceding claim characterised in that said information containing element is in the form of a micro-chip. A thermoplastic heat fusion pipe fitting according to any preceding claim and characterised in that the interrogator signal is produced by a fusion control unit (28) which also contains a decoder (27) to decode the signal transmitted by the element. A thermoplastic heat fusion pipe fitting according to any preceding claim and characterised in that the information containing element contains information selected from:- time and/or current and/or voltage required to effect fusion; type of fusion pipe fitting; material of which the fusion pipe fitting is manufactured; manufacturing details, source etc.; manufacturing details; source; temperature compensation; and special instructions to control unit or operator. A thermoplastic heat fusion pipe fitting according to any of claims 1 to 6 or 8 characterised by being in combination with a fusion control unit the fusion control unit containing a transmitter receiver (26) for interrogating the information containing element, a decoder (27), a fusion current control and timer unit (28), and a recorder (30). A fitting according to any preceding claim characterised in that the electrical heating element (14) is used as an antenna to receive and/or transmit signals.

Inventors: REEVES ANTHONY VINCENT, REEVES, ANTHONY VINCENT
Applicants: UPONOR BV
Application year: 1989
Main classification: B29C65
IPC codes: B29L31, G05B19, B29L23, B29C65, F16L47