Hiscox figure 387 identifies the Excelsior as a staged lifting-and-force injector. Separate steam admission starts lifting with overflow open; further handle movement closes the overflow and establishes delivery. Calculate static suction pressure, water vapour pressure and an entered delivery-pressure target. These quantities do not predict injector capacity.
Excelsior Injector Interactive Calculator
Watch the documented valve sequence and calculate hydrostatic suction pressure, water vapour pressure and a specified delivery-pressure target.
Equation Used
- Standard atmospheric-pressure reference.
- Static water column for suction lift.
- Water vapour pressure from the displayed correlation.
- No nozzle momentum, steam condensation rate, losses, capacity, commissioning or safe-operation model.
The delivery result is an entered design target, not proof the injector can attain it. The suction calculation assumes standard atmosphere and static water. Actual pickup and capacity require the maker's cone geometry, steam condition, losses and test data.
Hiscox figure 387 sequence
A separate valve admits steam to lifting nozzle A while overflow cock DC is open. The first handle movement opens conical valve b. Further movement closes DC to both the lifting passage and force overflow S, allowing the combined jet to enter the delivery passage.
The diagram follows the lifting, overflow and delivery stages. Nozzle geometry and steam-water mixing determine whether a particular injector can deliver at the required pressure.
Historical boiler-feed apparatus
The steam injector lifts feedwater and directs it toward the boiler. Selection and operation depend on the actual maker's cone set, valves, steam supply, water conditions and boiler installation.
Pressure checks used here
Static lift vacuum is rho g h. Suction absolute pressure is standard atmospheric pressure minus that lift. Water vapour pressure is calculated with an Antoine correlation over the calculator's temperature range. The displayed margin is suction absolute pressure minus vapour pressure.
Specified delivery target is boiler pressure multiplied by one plus the entered rise. None of these relations predicts entrainment, condensation or injector capacity.
How to interpret the numbers
A positive vapour-pressure margin is only a necessary suction-side check. It is not sufficient evidence that an injector will pick up or deliver. The delivery target similarly states the pressure the jet would need to overcome, not what a particular cone set produces.
Scope and limitations
This model omits compressible nozzle flow, steam quality, heat and momentum balances, cone dimensions, discharge coefficients, losses, overflow dynamics and check-valve behaviour. Use maker data and boiler practice for real equipment.
Questions
Does the calculator size an injector?
No. It supplies pressure-side planning checks only.
Why show the overflow?
Because the historical description makes its staged closing part of the Excelsior operating sequence.
Does positive pressure margin guarantee pickup?
No. It is necessary but not sufficient.
Primary reference
Building or designing a mechanism like this?
Explore the precision-engineered motion control hardware used by mechanical engineers, makers, and product designers.
