FLUID TRANSPORT TANKERS

Abstract: A fluid transport tanker comprises a barrier member arranged for movement respectively between a first position and a second position so as to either prevent or allow connection of a delivery conduit to one or more outlet valves of the tanker, there being pneumatically operable locking means (1) for the barrier member comprising a locking element (2) to retain the member in its first position. The tanker further comprises pneumatic control means including first and second pneumatic switches (7,8) operable in response to movement of the locking element so as to enable the tanker to be filled and to prevent movement of the tanker, the first switch (7) being connected to a pneumatic pressure source via at least one manually operable master shut-down switch, and the second switch (8) being connected to the same or a different pneumatic source independently of the shut-down switch.

Description: This invention relates to fluid transport tankers, such as road or rail tankers, and to pneumatic control means therefor. It is known to provide pneumatic control means in conjunction with e.g. road tankers for controlling the operation of various components associated with the tanker such as the inlet/outlet and vent valves, such means being intended both to increase safety as regards filling and delivery procedures in the case of toxic or inflammable fluids and also to reduce the possibilities for embezzlement. Such an arrangement is known from EP-A-0 129 488, wherein a pneumatic safety circuit includes a pressure switch connected via a pipe to a manually operated control valve. Under normal operation the control valve must be vented to atmosphere before a filler arm attached to the tanker can be disconnected. In the event that the tanker driver attempts to drive away without first disconnecting the filler arm, the pressure retained in the pipe acts on the pressure switch which in turn actuates a warning signal. In a further known arrangement such as US-A-4 024 897, the tanker is provided, as a security feature, with a barrier member typically in the form of an elongate bar or shield which is arranged e.g. for pivotal movement between a first position wherein it extends in front of the outlet valve or valves and a second position permitting access to the outlet valve(s) so that a delivery conduit can be connected thereto. In another known arrangement, pneumatically operable locking means for the barrier member are adapted to retain the member in its first position, such locking means being connected to a pneumatic control unit of the tanker and only being releasable in response to a pneumatic signal therefrom. Such arrangements help to avoid embezzlement by unauthorised personnel who do not have access to the control unit. In one known arrangement the locking means for the barrier member also forms part of a safety means for the tanker in that movement of a locking element of the locking means to release the barrier member is also effective to open a pneumatic switch which applies a pneumatic signal to actuate means preventing movement of the tanker. Such means may be effective to apply the tanker brakes or alternatively to inhibit the engine starting electrical circuit, and in either case the effect is to prevent movement of the tanker at all times when the barrier is unlocked. This avoids the possibility of the driver inadvertently moving the tanker when one or more of the outlet valves are connected to a delivery conduit, and also ensures that the tanker cannot be driven off after delivery has taken place with the operator having neglected to return the barrier to its first position and lock it therein. It has also been proposed, as an additional safety feature particularly applicable to tankers wherein filling is carried out by pumping in fluid under pressure via the same valves which are used to discharge the fluid, that a pneumatic signal from the switch associated with the locking means is additionally applied to a means which enables filling of the tanker to take place. Such means may be in the form of a pressure sensitive pneumatic switch coupled to an electrical switch arranged to isolate the pumping means for the tanker from its power source, so that the pumping means can only possibly be energised when the switch is turned on and thus only when the locking means for the barrier member is released. However, in known systems of this type it is desirable to provide at least one manually operable master shut down switch whereby the control means can be readily deactivated in an emergency, and problems in this respect can arise in the prior art arrangement discussed above in that disabling of the said means enabling filling of the tanker to take place also results in the means preventing movement of the tanker being disabled which is undesirable even in an emergency shut down condition of the control means. Viewed from one aspect the invention provides a fluid transport tanker comprising a barrier member arranged for movement between a first position wherein it is so located as to prevent connection of a delivery conduit to one or more outlet valves of the tanker and a second position wherein access may be gained to said valve(s) for connection of a delivery conduit thereto; characterised in there being pneumatically operable locking means for the barrier member comprising a locking element arranged to retain the member in its first position, such element being retractable in response to a pneumatic signal applied to the locking means to release the barrier member, there being pneumatic control means including first and second pneumatic switches respectively operable in response to retracting movement of said locking element to actuate means enabling filling of the tanker via said outlet valve(s) to take place and to actuate means preventing movement of the tanker, said first switch being connected to a pneumatic pressure source via at least one manually operable master shut down switch of the control means and said second switch being connected to the same or further pneumatic source independently of said shut-down switch. Viewed from a second aspect the invention provides a pneumatic control means for a tanker as aforesaid. Thus, in accordance with the invention whilst the safety features discussed above associated with the barrier member locking means are retained, problems concerning the possibility of disabling the tanker filling means and at the same time preventing movement of the tanker in an emergency condition are avoided. The means preventing movement of the tanker may take any convenient form, and typically may be adapted to apply the tanker brakes and/or disable the engine ignition and/or an electrical engine starting circuit in response to a pneumatic signal applied from said second switch. The means enabling filling to take place may also take any suitable form, and may typically comprise pneumatically responsive electrical switch means arranged in an electrical supply circuit for fluid inlet pumping means for the tanker whereby the pumping means can only be actuated when said switch means is turned "on" consequent upon a pneumatic signal being applied thereto from the first switch associated with the barrier member locking means. In a preferred such embodiment, the electical switch means is also responsive to a pneumatic switch means responsive to a vapour outlet conduit connection of the or each fluid container of the tanker and to a fluid sensor provided at the top of the container, so that the pumping means is also automatically disabled when there is no vapour outlet conduit connected to the container to collect vapour forced therefrom during filling, and when the container is full. In a particularly preferred embodiment the barrier member locking means and the first and second pneumatic switches responsive to movement of the locking element thereof form part of a common unit and viewed from a third aspect the invention provides such a unit for a tanker and for pneumatic control means therefor as aforesaid. Advantageously, the unit comprises a housing defining an elongage bore, and a plunger slidably mounted in the bore, a free end of said plunger being arranged to project from the housing and forming or being connected to said locking element, said first and second pneumatic switches each comprising respective axially spaced inlet and outlet ports communicating with said bore and sealing means associated with the plunger arranged to isolate said respective ports from one another in the locked condition of said element and to communicate said respective ports with one another when the locking element is retracted. It is also required that the housing includes an inlet port communicating with said bore arranged for the application of a pneumatic signal for retracting the plunger so as to release the locking element, and in a particularly advantageous arrangement such inlet port is common with the inlet port of the first pneumatic switch of the unit, so that the pneumatic signal applied to the means enabling filling of the tanker to take place is firstly used to retract the locking element. This has the advantage that a common pneumatic supply line connected to the pressure gas source via one or more master shut down switches may be used for retracting the plunger and for enabling filling so that the number of connections to the unit can be reduced. In a preferred embodiment the plunger is moved against the force of a biasing spring, in which case in the embodiment discussed above wherein the plunger actuating signal is applied via the master shut down switch(es), the locking element is preferably arranged to be held in its retracted condition by camming engagement with the barrier member when in its second position which ensures that the second switch is held open and the tanker is thus prevented from moving even in the event that a shut down switch of the control means is closed. A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, wherein: Figure 1 is a schematic diagram illustrating the locking means for the outlet valve barrier member of e.g. a road tanker together with the associated parts of the pneumatic control means; and Figure 2 illustrates in partial cross-section a preferred form of locking means and pneumatic switches associated therewith. Referring to the drawings, as shown schematically in Figure 1 a road tanker is provided with first and second locking means 1 provided adjacent each end of a barrier member (not shown) arranged, in a first position thereof, to extend in front of outlet valves of the tanker. The locking means 1 each include a locking element 2 retractable upon application of a pneumatic signal applied from a pneumatic control unit (not shown) via a first inlet line 3, the two locking means 1 being arranged in series in this respect. Thus, in their extended condition the locking elements 2 engage in complementary recesses associated with the barrier member to retain the member in its first condition wherein access may not be gained to the outlet valves of the tanker for connection of delivery conduits thereto. Upon retraction of the locking elements 2 consequent upon a pneumatic switch being operated in the control unit so as to apply a pneumatic signal via line 3, the barrier member is released and can be moved e.g. by pivoting away from the outlet valves. As shown in Figure 1, the downstream one of the locking means is connected via a further pneumatic line 4 to a pressure sensor 5 which is in turn coupled to an electrical switch arranged in the electrical power supply for a pumping means (not shown) used to pump fluid into the tanker. The line 4 is connected to the pressure sensor 5 via a pneumatic switch means 6 which is responsive firstly to a vapour outlet hose interlock and secondly to a level sensor provided inside the tanker adjacent the top wall thereof. Thus, the line 4 is only connected to the pressure sensor 5 when a hose is connected to the respective container of the tanker for release of vapour forced out during filling, and, furthermore, the pumping means is disabled when the container is full. As will be discused in more detail below in conjunction with Figure 2, the barrier member locking means each comprise first and second pneumatic switches 7, 8 which are opened when the locking element 2 is retracted. The first switches 7 are arranged in series to communicate the pneumatic line 3 with the line 4 and thus to apply a pneumatic signal via the switching means 6 to the pressure sensor 5. In this way, it will be appreciated that it is only possible to energise the pumping means when the locking elements are retracted. The pneumatic line 3 is connected to a pneumatic pressure gas source via one or more manually operable master shutdown switches (not shown) of the control means, so that in the event of such switches being closed in an emergency condition a pneumatic signal is no longer applied to the pressure sensor 5 and the pump means is thus disabled. As also shown in Figure 1, the second switch 8 of the downstream one of the locking means connects a futher pneumatic supply line 9 with a line 10 leading to means preventing movement of the tanker. Such means could be adapted to apply the tanker brakes and/or to disable the electrical starting circuit of the tanker. The line 9 is connected to the pneumatic gas source in a circuit which is separate from the master shutdown switches whereby in an emergency condition closing of the shutdown switches does not affect the movement preventing means. A preferred form of locking means 1 is illustrated in Figure 2 and comprises a housing 30 formed e.g. of aluminium having formed therein an elongate bore 11 in which a plunger 12, the front end of which forms the locking element 2, is slidably mounted. The first and second switches 7, 8 include respective inlet and outlet ports 13, 14; 15, 16 which are axially spaced and which communicate with the bore 11. Sealing means in the form of O-rings 20 are carried by the plunger so that in the extended condition of the locking element shown in elevation in the lower part thereof in Figure 2, the respective inlet and outlet ports 13, 14; 15, 16 are isolated from one another. Upon application of a pneumatic signal via line 3 to inlet port 13, the plunger 12 is urged rightwardly as shown in Figure 2 against the force of a biasing spring 21 so that, as shown in section in the upper part of the Figure, the respective ports 13, 14; 15, 16 are communicated with one another. A port 22 open to atmosphere is provided to permit release of air from the region behind the plunger as it is moved between its extended and retracted positions. As shown in Figure 2, the preferred locking means and associated switch means constitutes a simple and robust unit, the bore being closed at the end remote from the locking element 2 by means of a plug 25 arranged to seat the spring 21 and retained in place via a circlip 26. Apertures 27 are provided whereby the unit may be secured by means of mounting bolts in a desired location adjacent the barrier member. Whilst certain broad aspects and specific features of apparatus have been described and illustrated herein, modifications may be apparent to those of relevant skill which retain one or more of the advantages thereof.

Claims: A fluid transport tanker comprising a barrier member arranged for movement between a first position wherein it is so located as to prevent connection of a delivery conduit to one or more outlet valves of the tanker, and a second position wherein access may be gained to said valve(s) for connection of a delivery conduit thereto; characterised in there being pneumatically operable locking means (1) for the barrier member comprising a locking element (2) arranged to retain the member in its first position, such element (2) being retractable in response to a pneumatic signal applied to the locking means (1) to release the barrier member, there being pneumatic control means including first and second pneumatic switches (7,8) respectively operable in response to retracting movement of said locking element (2) to actuate means enabling filling of the tanker via said outlet valve(s) to take place and to actuate means preventing movement of the tanker, said first switch (7) being connected to a pneumatic pressure source via at least one manually operable master shut down switch of the control means and said second switch being connected to the same or further pneumatic source independently of said shut-down switch. A fluid transport tanker as claimed in claim 1 wherein said means preventing movement of the tanker is adapted to apply the tanker brakes. A fluid transport tanker as claimed in claim 1 wherein said means preventing movement of the tanker is adapted to disable the engine ignition. A fluid transport tanker as claimed in claim 1 wherein said means preventing movement of the tanker is adapted to disable an electrical engine starting circuit. A fluid transport tanker as claimed in any preceding claim wherein means enabling filling to take place comprise pneumatically responsive electrical switch means (5) arranged in an electrical supply circuit for fluid inlet pumping means for the tanker whereby the pumping means can only be actuated when said switch means (5) is turned "on" consequent upon a pneumatic signal being applied thereto from the first switch (7) associated with barrier member locking means (1). A fluid transport tanker as claimed in claim 5 wherein said electrical switch means (5) is also controlled by a pneumatic switch means (6) responsive to a vapour outlet conduit connection of the or each fluid container of the tanker and to a fluid sensor provided at the top of the container. A fluid transport tanker as claimed in any preceding claim wherein the barrier member locking means (1) and the first and second pneumatic switches (7,8) of the control means responsive to movement of the locking element (2) thereof form part of a common unit. A fluid transport tanker as claimed in claim 7 wherein the unit comprises a housing (30) defining an elongate bore (11), and a plunger (12) slidably mounted in the bore, a free end of said plunger being arranged to project from the housing and forming or being connected to said locking element (2), said first and second pneumatic switches (7,8) each comprising respectively axially spaced inlet and outlet ports (13,14; 15,16) communicating with said bore and sealing means (20) associated with the plunger arranged to isolate said respective ports from one another in the locked condition of said element and to communicate said respective ports with one another when the locking element (2) is retracted, said housing further comprising an inlet port (13) communicating with said bore arranged for the application of a pneumatic signal for retracting the plunger so as to release the locking element. A fluid transport tanker as claimed in claim 8 wherein said inlet port (13) is common with the inlet port (13) of the first pneumatic switch (7) of the unit. A fluid transport tanker as claimed in claim 8 or 9 wherein said plunger (12) is moved against the force of a biasing spring (21). A fluid transport tanker as claimed in any of claims 7 to 10 wherein said locking element (2) is arranged to be held in its retracted condition by camming engagement with the barrier member when in its second position.

Inventors: JAMES, SIMON
Applicants: EMCO WHEATON U.K. LIMITED
Application year: 1987
Main classification: B65D90
IPC codes: B65D90