Illustrative c5 expansion vessel example
96.0 L ideal required vessel; 120 L candidate; pressure release heldmodeled
| Value kind | modeled — Interpret this value according to its displayed kind, scope, source, and as-of date. |
|---|---|
| Scope | Assume 1,000 L liquid inventory specified to three significant figures and a supplier-provided fractional expansion of 0.0200 between fill and maximum temperature. An ideal bladder vessel has 2.50 bar absolute precharge, 3.00 bar absolute cold fill and 4.00 bar absolute hot static pressure, with isothermal gas behavior, usable nominal volume and no reserve loss. Candidate nominal vessel volume is 120 L. For a separate worst-node pressure screen assume 1.00 bar ambient pressure, no elevation change at that node, all operating or shutoff pump differential additive to hot static pressure, 3.00 bar pump shutoff differential, and a 6.00 bar gauge weakest-component limit. Operating differential comes unrounded from the hydraulic case. These simplified geometry and gas assumptions are bounded by this chapter; actual fluid expansion and vessel acceptance must come from the selected formulation and vessel. |
| As of | 2026-09 |
| Source | Guide calculation from expressly assumed teaching inputs. Primary reference supplies method or equipment context, not evidence that this design was built or tested. |
| Derivation | Decision: provide expansion acceptance and a separate overpressure path before filling the loop. Fluid growth is 1,000 L × 0.0200 = 20.0 L . Isothermal gas volume is Vgas = Vvessel × pprecharge/pabsolute. Acceptance between cold and hot conditions is therefore Vvessel × (2.50/3.00 − 2.50/4.00) = 0.208Vvessel. Required ideal vessel volume is 20.0/0.208333… = 96.0 L ; the 120 L candidate accepts 25.0 L and clears this ideal screen by 5.00 L. The hot static pressure is 4.00 − 1.00 = 3.00 bar gauge. Add the computed 2.38 bar operating differential to obtain 5.38 bar gauge at the assumed worst node, leaving 0.617 bar below the 6.00 bar component limit. At shutoff, 3.00 + 3.00 = 6.00 bar gauge : the circuit has no pressure reserve before transient or relief-setting tolerances. Select the candidate vessel for further qualification but hold the pressure-system release until the shutoff, surge and relief design clears every component. Expansion acceptance does not protect an isolated heated pocket from overpressure. Flip the vessel: its exact expansion crossover is 25.0/1,000 = 0.0250, or 2.50%; above that growth the candidate fails even the ideal model. Reducing hot static pressure below 4.00 bar absolute or increasing the qualified component limit opens shutoff reserve, but changes the NPSH or equipment selection and requires recalculation. The pressure-vessel supplier must provide the usable acceptance curve and relief arrangement; the ASME B31.9 scope identifies a candidate piping code, while the ideal-gas balance is a guide derivation. Hand the complete pressure envelope and approved code basis to Chapter 13.5 . |
| Review | checking…cadence-derived review 2027-01-03 · standard cadence |
| Recorded changes | none recorded |
| Claim id | p5-c5-expansion-vessel-example |
Where the guide uses it
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