A system for determining a saturation pressure of a liquid comprising: a) a probe assembly including: i) a manifold having at internal passage; ii) an elongated bulb defining a chamber and including a distal tip portion and a proximal portion, said bulb secured to the manifold by the proximal portion with the chamber containing a pressurized vapor and in fluid communication with the internal passage; iii) a charging port selectively in fluid communication with the internal passage of the manifold; and iv) a pressure transmitter configured to detect a pressure within the chamber of the elongated bulb; b) a jacketed pipe assembly including: i. a pipe defining a flow passage; ii. a jacket surrounding the pipe so that a first annular space is formed, said annular space being at least partially evacuated of air; iii. a probe port to which said probe assembly is attached and configured so that the distal tip portion of the bulb is positioned within the flow passage of the pipe, said probe port including an inner sleeve defining a central bore that is configured to receive the elongated bulb, an end cap fitting having a central opening configured to receive the elongated bulb and an outer sleeve surrounding the inner sleeve so that a second annular space is defined between the inner and outer sleeves and the end cap fitting, wherein the second annular space in fluid communication with the first annular space and wherein the probe assembly is removably attached to the end cap fitting by an attachment member. a) a probe assembly including: i) a manifold having at internal passage; ii) an elongated bulb defining a chamber and including a distal tip portion and a proximal portion, said bulb secured to the manifold by the proximal portion with the chamber containing a pressurized vapor and in fluid communication with the internal passage; iii) a charging port selectively in fluid communication with the internal passage of the manifold; and iv) a pressure transmitter configured to detect a pressure within the chamber of the elongated bulb; i) a manifold having at internal passage; ii) an elongated bulb defining a chamber and including a distal tip portion and a proximal portion, said bulb secured to the manifold by the proximal portion with the chamber containing a pressurized vapor and in fluid communication with the internal passage; iii) a charging port selectively in fluid communication with the internal passage of the manifold; and iv) a pressure transmitter configured to detect a pressure within the chamber of the elongated bulb; b) a jacketed pipe assembly including: i. a pipe defining a flow passage; ii. a jacket surrounding the pipe so that a first annular space is formed, said annular space being at least partially evacuated of air; iii. a probe port to which said probe assembly is attached and configured so that the distal tip portion of the bulb is positioned within the flow passage of the pipe, said probe port including an inner sleeve defining a central bore that is configured to receive the elongated bulb, an end cap fitting having a central opening configured to receive the elongated bulb and an outer sleeve surrounding the inner sleeve so that a second annular space is defined between the inner and outer sleeves and the end cap fitting, wherein the second annular space in fluid communication with the first annular space and wherein the probe assembly is removably attached to the end cap fitting by an attachment member. i. a pipe defining a flow passage; ii. a jacket surrounding the pipe so that a first annular space is formed, said annular space being at least partially evacuated of air; iii. a probe port to which said probe assembly is attached and configured so that the distal tip portion of the bulb is positioned within the flow passage of the pipe, said probe port including an inner sleeve defining a central bore that is configured to receive the elongated bulb, an end cap fitting having a central opening configured to receive the elongated bulb and an outer sleeve surrounding the inner sleeve so that a second annular space is defined between the inner and outer sleeves and the end cap fitting, wherein the second annular space in fluid communication with the first annular space and wherein the probe assembly is removably attached to the end cap fitting by an attachment member.