A vacuum system pipe coupling includes a first coupling member defining a through passage, a second coupling member defining a through passage and a securing unit. The first coupling member has a first end portion having a first lengthways extending axis, a second end portion having a second lengthways extending axis that is laterally offset with respect to the first lengthways extending axis and a first connecting portion connecting the first and second end portions. The second coupling member has a third end portion having a third lengthways extending axis, a fourth end portion having a fourth lengthways extending axis that is laterally offset with respect to the third lengthways extending axis and a second connecting portion connecting the third and fourth end portions. The securing unit is configured to secure the first end portion to the third end portion with the first and third lengthways extending axes in alignment.

A vacuum pumping and/or abatement system for evacuating and/or abating fluid from an entity, the system comprising: a first module comprising a vacuum pumping apparatus for pumping the fluid from the entity and/or an abatement apparatus for abating the fluid evacuated from the entity; and a second module arranged adjacent to the first module in a first system dimension; wherein the first and second modules each have a maximum size in the first system dimension that is a respective integer multiple of a common fixed system value.

A vacuum pumping and/or abatement system for evacuating and/or abating fluid from an entity, the system comprising: a first module comprising a vacuum pumping apparatus for pumping the fluid from the entity and/or an abatement apparatus for abating the fluid evacuated from the entity; and a second module arranged adjacent to the first module in a first system dimension; wherein the first and second modules each have a maximum size in the first system dimension that is a respective integer multiple of a common fixed system value.

A fluid heater includes: a passage member having a passage formed therein; a heater for heating the passage member; a fixing member for fixing the passage member to a fluid control device; and a connection member connected to the passage member so as to allow fluid to flow into the passage member. The passage has a helical shape.

There is described a system comprising an outer conduit; an inner conduit positioned within the outer conduit such that an annular space is defined between the outer conduit and the inner conduit; and a resistive heating material occupying at least a portion of an annular volume within the annular space and having a positive temperature coefficient of resistance.

There is described a system comprising an outer conduit; an inner conduit positioned within the outer conduit such that an annular space is defined between the outer conduit and the inner conduit; and a resistive heating material occupying at least a portion of an annular volume within the annular space and having a positive temperature coefficient of resistance.

An internal heating trace assembly may include a first bus bar, a second bus bar, a plurality of ceramic positive temperature coefficient (PTC) elements, and an insulator. The ceramic PTC elements may be disposed in parallel between the first bus bar and the second bus bar. The insulator may include a heat-shrink tubing. The ceramic PTC element may include a PTC strip or a PTC bead.

A plug connector including a coupling part with a receiving opening into which a plug part, having a plug shaft with a collar, can be inserted. The plug connector also includes a resilient, radially slotted retaining clip having at least two spring arms and which can be pre-assembled on the coupling part and moved radially between an insertion position and a holding position for the plug part. The plug part can be inserted into the receiving opening when the retaining clip is in the insertion position, and when in the holding position he plugged-in plug part, and the collar thereof, can be blocked by the retaining clip against being pulled out. In the insertion position, the retaining clip projects with respect to the outer circumference of the coupling part, and in the holding position the retaining clip is flush with the outer circumference of the coupling part.

A plug connector including a coupling part with a receiving opening into which a plug part, having a plug shaft with a collar, can be inserted. The plug connector also includes a resilient, radially slotted retaining clip having at least two spring arms and which can be pre-assembled on the coupling part and moved radially between an insertion position and a holding position for the plug part. The plug part can be inserted into the receiving opening when the retaining clip is in the insertion position, and when in the holding position he plugged-in plug part, and the collar thereof, can be blocked by the retaining clip against being pulled out. In the insertion position, the retaining clip projects with respect to the outer circumference of the coupling part, and in the holding position the retaining clip is flush with the outer circumference of the coupling part.

A pipe heating device for preventing freezing of pipes includes a controller and a plurality of heating elements. The heating elements are operationally coupled to the controller and each heating element is configured to selectively couple to a respective pipe of a plumbing assembly. The controller is positioned to selectively power the heating element so that the heating element is configured to maintain water that is positioned in the respective pipe in a fluid state.