Abstract: A backup ring is for contacting with and supporting a plunger seal which is for sealing a pump chamber provided in a pump head of a plunger type liquid feeding pump. The backup ring includes a maximum outer diameter portion of a cylindrical shape and a smaller outer diameter portion. The maximum outer diameter portion includes a maximum outer diameter in a plunger seal supporting surface side that makes contact with a rear surface of the plunger seal. The smaller outer diameter portion includes a smaller outer diameter than the maximum outer diameter portion in at least one part of a portion other than the maximum outer diameter portion.

Abstract: A plunger pump includes, independently of a pump head, a pressure detection apparatus independently having a sensor part for detecting a fluid pressure, and the pump head and the pressure detection apparatus are detachably mounted with a communication member sandwiched between them. Therefore, when the pressure detection apparatus fails, only the pressure detection apparatus can be replaced, and the pump head can be used as it is without replacement.

Abstract: A liquid sending failure detector acquires periodically a liquid sending pressure of a liquid sending mechanism consecutively sends liquid using at least one plunger pump that sends liquid by reciprocally driving a plunger such that a fluctuation is read in one driving period of the liquid sending mechanism, and detect a liquid sending failure of the liquid sending mechanism using an acquired liquid sending pressure. The liquid sending failure detector executes a pulsation detection step of obtaining a fluctuation range of the liquid sending pressure in a certain driving period of the liquid sending mechanism and detecting pulsation on a condition that a count of consecutive periods in which the fluctuation range exceeds a predetermined reference value exceeds a predetermined reference count, and a liquid sending failure detection step of detecting a liquid sending failure of the liquid sending mechanism when the pulsation is detected in the pulsation detection step.

Abstract: The liquid feeding device includes a discharge speed calculation part configured to calculate a discharge speed v of the plunger pump so that a converted value LATM under an atmospheric pressure of a flow rate LPRE of the mobile phase discharged to the discharge channel from the pump part becomes a set flow rate LSET using a volume V of the mobile phase in the pump chamber of the closing pump immediately before the precompression process is started, a volume ?V reduced due to the precompression process of the mobile phase in the pump chamber of the closing pump, and a feeding pressure P; and a discharge operation controller configured to control a discharge speed of the plunger pump to a discharge speed v calculated by the discharge speed calculation part.

Abstract: A plunger pump includes, independently of a pump head, a pressure detection apparatus independently having a sensor part for detecting a fluid pressure, and the pump head and the pressure detection apparatus are detachably mounted with a communication member sandwiched between them. Therefore, when the pressure detection apparatus fails, only the pressure detection apparatus can be replaced, and the pump head can be used as it is without replacement.

Abstract: The liquid feeding device includes a discharge speed calculation part configured to calculate a discharge speed v of the plunger pump so that a converted value LATM under an atmospheric pressure of a flow rate LPRE of the mobile phase discharged to the discharge channel from the pump part becomes a set flow rate LSET using a volume V of the mobile phase in the pump chamber of the closing pump immediately before the precompression process is started, a volume ?V reduced due to the precompression process of the mobile phase in the pump chamber of the closing pump, and a feeding pressure P; and a discharge operation controller configured to control a discharge speed of the plunger pump to a discharge speed v calculated by the discharge speed calculation part.

Abstract: A backup ring is for contacting with and supporting a plunger seal which is for sealing a pump chamber provided in a pump head of a plunger type liquid feeding pump. The backup ring includes a maximum outer diameter portion of a cylindrical shape and a smaller outer diameter portion. The maximum outer diameter portion includes a maximum outer diameter in a plunger seal supporting surface side that makes contact with a rear surface of the plunger seal. The smaller outer diameter portion includes a smaller outer diameter than the maximum outer diameter portion in at least one part of a portion other than the maximum outer diameter portion.