Pumps, valves, probes, fittings, tubing and sensing components for precise sample preparation, reagent handling and instrument fluidics.
High-Pressure Valves for Sample-Loop Injection
Application guide · High-pressure injection
A high-pressure injection valve separates low-pressure sample loading from the pressurized analytical stream. Specify the loop, rotor state and fittings as one injection assembly; the low-pressure metering pump fills the loop but does not replace the chromatographic mobile-phase pump.
Engineering example: a nominal 20 μL loop may be filled by a larger sample volume so the loop contents approach the source composition. The required excess depends on loop and connecting volume, dispersion and the accepted injection method; 20 μL delivered to the inlet is not automatically a 20 μL injected plug.[1][2]
01Define the liquid, receiver and complete duty before selecting the component
Translate the analytical task into an engineering duty
Use case
Inputs to define
Decision supported
Loop loading
Sample amount, loading pressure and waste path
Fill without trapping gas or contaminating the high-pressure side
Injection
System pressure, allowed pressure disturbance and switching time
Move the defined loop into the mobile phase
Wash/recovery
Needle, loading line and loop-cleaning sequence
Restore a valid blank before the next sample
02Calculate the working point and the margin the instrument really needs
Calculations to complete before prototype selection
Quantity
How to define it
Why it matters
Loop volume
Method injection volume and loading mode
Choose full-loop, partial-loop or overfill deliberately
Loading requirement
loop + connector volume + method overfill
Sizes the low-pressure sample supply
Pressure envelope
all port pressures during and after switching
Determines valve, loop and fitting rating
Use minimum, routine and maximum conditions rather than one nominal point. Include the first cycle after priming or idle, the lowest source level, the highest expected restriction and the actual receiving geometry. A nominal capacity, free-flow value or theoretical command increment is not an acceptance result.
03Map the task to a FOREACH configuration and the rest of the fluid path
04Program the full liquid cycle, including prime, wash and recovery
Set load state→Rinse loading path→Fill loop to method condition→Stabilize pressure→Switch to inject state→Return, wash and verify blank
A complete method cycle is more than the active delivery step
The exact physical order and parallel actions depend on the instrument. Retain each state in the control and verification plan.
Record valve states, motion, dwell, sensor windows and rejected recovery cycles. This makes throughput and liquid consumption auditable and prevents a fast component movement from being reported as the complete analyzer cycle.
05Design abnormal-state diagnosis before the fault occurs
Observed result, likely mechanism and useful next action
Observed condition
Likely mechanism
Engineering response
Injection area varies
Incomplete loop fill, bubbles or timing
Check loading volume and state sequence
Pressure transient
Switching or fitting mismatch
Review rotor timing and port connections
Peak broadening
Excess connection volume or bore mismatch
Use matched zero/low-dead-volume interfaces
The controller should distinguish a recoverable event from a result-invalidating event. A retry is useful only after the original cause has been removed and the liquid path has returned to a verified state.
06Accept performance where the liquid is actually used
Minimum qualification plan for the integrated channel
Result
Where or how to measure
Acceptance question
Injected amount
Applicable standard and detector response
Repeatable under the actual loading method
Pressure integrity
Maximum operating and switching states
No leak or unacceptable transient
Carryover
High sample followed by blank
Meets method threshold after qualified wash
Test the exact liquid and complete wetted path at minimum, routine and maximum conditions.
Separate first-cycle, steady-state and post-idle results; do not average away recovery behavior.
Challenge the relevant fault and confirm the controller prevents an invalid result from being accepted.
Retain the configuration, software sequence, consumables and receiving-position result together as the qualification record.
