Functions
Param	_p (float value, str unit)
ReliefValve	_relief (float cv=5.0, **Param extra)
	_helium (float p, float T=293.15, float lift=1.0)
None	test_gas_flow_is_iec_60534_as_fluids_implements_it (float\|None x)
None	test_rated_capacity_by_hand ()
None	test_shut_below_set_opens_at_set_and_reseats_with_hysteresis ()
None	test_without_a_session_a_relief_is_shut ()
None	test_the_model_block_names_its_sources_and_inputs ()
dict	_drawing (dict\|None rv_params)
dict	_rv_params (float cv, float\|None set_psi)
None	test_an_rv_without_a_set_pressure_is_shut_and_says_so ()
None	test_an_rv_with_a_set_pressure_is_a_relief_on_the_ullage ()
None	test_shipped_drawings_have_no_relief_and_build_as_before ()
None	test_a_relief_holds_the_fuel_tank_when_the_regulator_fails_open ()

Variables
	STAR = Path(__file__).resolve().parents[3]
str	DRAWINGS = STAR / "feed-twin" / "backend" / "diagrams"
str	HE = DRAWINGS / "copv_study_he.json"
str	TABLES = STAR / "feed-twin" / "backend" / "statemachines"
	needs_drawing
float	SET_PSI = 750.0
float	BORE_MM = 10.92

Detailed Description

The pressure relief valve (``relief_valve``, model ``spring``).

Checked against things that are not this code:

* its gas capacity, choked and not, against ``fluids``' own implementation of
  IEC 60534-2-1 (``size_control_valve_g``), which returns the Cv that passes a
  flow -- the valve's own Cv must come back;
* its lift law against ISO 4126-1's terms, by hand: shut below set, open at set,
  shut again only below set x (1 - blowdown);
* on the helium hot-fire drawing, a regulator failed wide open into the fuel
  tank: the tank must be held under set x (1 + overpressure), and with the
  regulator back it must vent down past set to the reseating pressure before the
  valve shuts.

And the drawing contract: an RV that declares no set pressure never lifts, so
it is read as shut -- no branch at all -- and the build says so. (It used to be
built as an always-open Cv valve: a hole to atmosphere on the tank it guards,
which on a pid-designer drawing like LE4's meant the stand could never hold
press.)

Function Documentation

◆ _drawing()

dict test_relief._drawing ( dict | None rv_params )

protected

Definition at line 188 of file test_relief.py.

Referenced by test_a_relief_holds_the_fuel_tank_when_the_regulator_fails_open(), test_an_rv_with_a_set_pressure_is_a_relief_on_the_ullage(), and test_an_rv_without_a_set_pressure_is_shut_and_says_so().

◆ _helium()

test_relief._helium	(	float	p,
		float	T = 293.15,
		float	lift = 1.0 )

protected

Definition at line 74 of file test_relief.py.

Referenced by test_gas_flow_is_iec_60534_as_fluids_implements_it(), test_rated_capacity_by_hand(), and test_without_a_session_a_relief_is_shut().

◆ _p()

Param test_relief._p	(	float	value,
		str	unit )

protected

Definition at line 56 of file test_relief.py.

Referenced by _relief().

◆ _relief()

ReliefValve test_relief._relief	(	float	cv = 5.0,
		**Param	extra )

protected

Definition at line 60 of file test_relief.py.

References _p().

Referenced by test_gas_flow_is_iec_60534_as_fluids_implements_it(), test_rated_capacity_by_hand(), test_shut_below_set_opens_at_set_and_reseats_with_hysteresis(), test_the_model_block_names_its_sources_and_inputs(), and test_without_a_session_a_relief_is_shut().

◆ _rv_params()

dict test_relief._rv_params	(	float	cv,
		float \| None	set_psi )

protected

Definition at line 231 of file test_relief.py.

Referenced by test_a_relief_holds_the_fuel_tank_when_the_regulator_fails_open(), test_an_rv_with_a_set_pressure_is_a_relief_on_the_ullage(), and test_an_rv_without_a_set_pressure_is_shut_and_says_so().

◆ test_a_relief_holds_the_fuel_tank_when_the_regulator_fails_open()

None test_relief.test_a_relief_holds_the_fuel_tank_when_the_regulator_fails_open ( )

The dome regulator failed wide open (dome above the bottle) into the fuel
tank alone, a relief set at 750 psig on the tank. Half full, so the ullage
is litres rather than the shipped 0.43 L and the test runs in seconds.

Below set the relief is shut. Failed open, the tank pops it and is held
under set + 10 % (the overpressure at which the valve is at full lift) with
the relief passing what the regulator delivers. Regulator restored, the tank
vents down *past* set to the reseating pressure before the valve shuts.

Definition at line 295 of file test_relief.py.

References _drawing(), _rv_params(), and max.

◆ test_an_rv_with_a_set_pressure_is_a_relief_on_the_ullage()

None test_relief.test_an_rv_with_a_set_pressure_is_a_relief_on_the_ullage ( )

Definition at line 266 of file test_relief.py.

References _drawing(), and _rv_params().

◆ test_an_rv_without_a_set_pressure_is_shut_and_says_so()

None test_relief.test_an_rv_without_a_set_pressure_is_shut_and_says_so ( )

Definition at line 252 of file test_relief.py.

References _drawing(), and _rv_params().

◆ test_gas_flow_is_iec_60534_as_fluids_implements_it()

None test_relief.test_gas_flow_is_iec_60534_as_fluids_implements_it ( float | None x )

Choked (x None: discharge to atmosphere) and not: ``fluids`` sizes the
valve for the flow this one passes, and returns this valve's Cv.

Definition at line 84 of file test_relief.py.

References _helium(), and _relief().

◆ test_rated_capacity_by_hand()

None test_relief.test_rated_capacity_by_hand ( )

W = N6 C (2/3) sqrt(F_gamma xT p1 rho1), IEC 60534-2-1 with N6 = 2.73
(Cv; kg/h, kPa, kg/m^3), helium (gamma 5/3) at 825 psig and 293.15 K.

Definition at line 124 of file test_relief.py.

References _helium(), and _relief().

◆ test_shipped_drawings_have_no_relief_and_build_as_before()

None test_relief.test_shipped_drawings_have_no_relief_and_build_as_before ( )

Definition at line 278 of file test_relief.py.

◆ test_shut_below_set_opens_at_set_and_reseats_with_hysteresis()

None test_relief.test_shut_below_set_opens_at_set_and_reseats_with_hysteresis ( )

Definition at line 137 of file test_relief.py.

References _relief().

◆ test_the_model_block_names_its_sources_and_inputs()

None test_relief.test_the_model_block_names_its_sources_and_inputs ( )

Definition at line 175 of file test_relief.py.

References _relief().

◆ test_without_a_session_a_relief_is_shut()

None test_relief.test_without_a_session_a_relief_is_shut ( )

Definition at line 163 of file test_relief.py.

References _helium(), and _relief().

Variable Documentation

◆ BORE_MM

float test_relief.BORE_MM = 10.92

Definition at line 53 of file test_relief.py.

◆ DRAWINGS

str test_relief.DRAWINGS = STAR / "feed-twin" / "backend" / "diagrams"

Definition at line 44 of file test_relief.py.

◆ HE

str test_relief.HE = DRAWINGS / "copv_study_he.json"

Definition at line 45 of file test_relief.py.

◆ needs_drawing

test_relief.needs_drawing

Initial value:

=  pytest.mark.skipif(
    not (HE.exists() and TABLES.is_dir()), reason="helium drawing or tables absent"
)

Definition at line 48 of file test_relief.py.

◆ SET_PSI

float test_relief.SET_PSI = 750.0

Definition at line 52 of file test_relief.py.

◆ STAR

test_relief.STAR = Path(__file__).resolve().parents[3]

Definition at line 43 of file test_relief.py.

◆ TABLES

str test_relief.TABLES = STAR / "feed-twin" / "backend" / "statemachines"

Definition at line 46 of file test_relief.py.

Functions

Variables

Detailed Description

Function Documentation

◆ _drawing()

◆ _helium()

◆ _p()

◆ _relief()

◆ _rv_params()

◆ test_a_relief_holds_the_fuel_tank_when_the_regulator_fails_open()

◆ test_an_rv_with_a_set_pressure_is_a_relief_on_the_ullage()

◆ test_an_rv_without_a_set_pressure_is_shut_and_says_so()

◆ test_gas_flow_is_iec_60534_as_fluids_implements_it()

◆ test_rated_capacity_by_hand()

◆ test_shipped_drawings_have_no_relief_and_build_as_before()

◆ test_shut_below_set_opens_at_set_and_reseats_with_hysteresis()

◆ test_the_model_block_names_its_sources_and_inputs()

◆ test_without_a_session_a_relief_is_shut()

Variable Documentation

◆ BORE_MM

◆ DRAWINGS

◆ HE

◆ needs_drawing

◆ SET_PSI

◆ STAR

◆ TABLES