--- title: Choosing a product — ruling families out description: When a family is ruled out, when it only warns, and how families the customer names are checked. sidebar: label: Choosing — ruling out order: 7 --- 9 rules, in register order, from R23 to R26; numbers do not run in sequence. [Back to the index](/business/business-rules). ## R23 — Among limitation entries, a family is ruled out only when a known value breaches a trusted hard limit or not-suitable entry Apart from the gates in R27 (output, readout, form factor, offered only when named, a family's own inputs) and sizing (R29), nothing else rules a family out. Known means stated by the customer, saved by a reviewer, or a property of a fluid matched to the library. A stated conductivity bound such as "< 0.1 µS/cm" counts when every value it allows breaches the limit (R126). A value within 0.0005 of a limit counts as at the limit, since a limit converted from another unit is held to three decimals: a stated 5 kg/cm² meets a 5 kg/cm² maximum held as 4.903 bar, and is not below 5 kg/cm². A limit for one phase rules a family out only when the phase is stated or comes from the matched fluid. A value the line does not hold, or holds only in words, can't be checked and rules out nothing. A limit can be linked to one option of a datasheet header, a PTFE lining on the lining header, say. When the line states an option of that header (stated, saved by a reviewer or mapped by Jev; Custom and wording no option matches do not count), the limit is judged as any other and can rule the family out if it is that option. When the line states a different option of that header, the limit does not apply. When the line states none, a breach only warns and those options leave the header's menu, the family staying; a family whose every option but Custom is left out is ruled out, naming the limits, since Custom never rescues a family from a breach of every listed construction. A linked limit that holds for one phase or condition only warns and does not trim the menu. Custom is never linked. A line-size limit that leaves out a size the item master releases warns only. A key limitation warns, an installation or recommendation entry is a note, and an ideal-use entry only ranks (R28). A level switch's number of set points is read from its stated set-point option, else from how many switching levels it states, else from wording such as high/low; a default never counts. ## R24 — A breach of an assumed value, an assumed phase, a guessed fluid or a condition FlowOS can't check warns; it never rules a family out An assumed range end or design value (R65, R68) is the exception: its breach is noted on the family, said to rest on an assumed figure, and neither warns nor rules out, so it never moves a family down the order (R28). The assumed ambient operating figure itself still warns, as it counts as known (R16). Flowtech's own guide and documents are trusted alone. A limit or a fluid property taken from other makers' pages needs two independent sources that agree; with one source it warns. A density written under 20 kg/m³ on a line that is not gas or steam is read as a specific gravity and only warns; a gas or steam phase guessed from the fluid's name alone, such as N2, keeps a figure written in kg/m³ as a density, but not one written with no unit. A library gas that may be liquid at the line's conditions (liquefied, cryogenic, or commonly handled as a liquid) is only warned of, through phase, density and viscosity. ## R121 — A fluid property from the library that would rule the product out, but only warns, is asked of the customer When the matched fluid's library property breaches a trusted hard limit or not-suitable entry of the line's product, but only warns because the figure is in doubt (the enquiry states one FlowOS cannot read, its source is single, or it is the library's figure at another temperature), the product stays with its warning (R23, R24) and the line asks the customer to confirm the property: under **Ask the customer** in line review and in **Raise query**, even once the line is confirmed, and as a warning on its quotation line. The question is cleared once the line holds a figure FlowOS reads, which then passes or rules the product out. An RO permeate line on an electromagnetic flowmeter whose enquiry states "Conductivity >10 µS/cm" is asked to confirm its conductivity. A breach of an assumed operating condition is not asked this way, and DM, deionized and distilled water are never asked: they rule the electromagnetic flowmeter out (R99). ## R99 — DM, deionized and distilled water never take an electromagnetic flowmeter They are non-electrolytic, so an electromagnetic flowmeter cannot read them, whatever conductivity the enquiry states. A line whose fluid is matched to one of the three rules the electromagnetic flowmeter out; a vortex or turbine flowmeter is offered in its place (R88). The rule is one of Flowtech's selection rules, on the Product Limitations screen. A guessed fluid only warns (R24). ## R100 — A vortex flowmeter on a liquid is checked for cavitation at its size The meter's pressure loss grows with the velocity at its bore at the line's maximum flow. The line's lowest operating pressure must reach that loss plus 2.6 times it and 1.25 times the liquid's vapour pressure at the line's hottest operating temperature, never its design temperature, as Flowtech's vortex brochure and other makers work it out. A pressure the line states decides over the range assumed around it (R65), and an ambient pressure is read as atmospheric, 0 bar g (R17). Water and water-based fluids take their vapour pressure from steam tables, other liquids from the fluid library where it holds one; where none is known, the line needs at least 1 bar g. A vortex that would cavitate is sized up while a larger size still reads the flow (R29); with none, it is ruled out, naming the velocity, the temperature, the pressure it needs and the pressure the line holds. A check resting on an assumed pressure, temperature or flow, an inferred phase, or a library density a liquid 10% lighter would pass, only warns (R24), and does not size up. ## R104 — A hazardous fluid rules out glass and acrylic body rotameters A fluid in the library may hold an NFPA 704 health rating, from 0 to 4, each with its sources. A rating of 3 or 4 rules out the glass tube, by-pass glass tube, tiny glass tube and acrylic body rotameters when two independent sources give that rating; otherwise it only warns (R24), and the customer is not asked, since a second source in the library settles it. A rating of 2 warns. A rating of 0 or 1, or no rating, changes nothing, and metal tube rotameters are never affected. A guessed fluid is not checked. The rules are Flowtech's selection rules, on the Product Limitations screen. ## R124 — A family marked analogue is not suggested to a line that asks for digital, and a digital one is not suggested to a line that asks for analogue Each flow meter and rotameter family is marked **Analogue** (read by eye on a needle, float or dial), **Digital** (read on an electronic display) or **Both**, on the family's page. A family left **Not set** is not filtered. A line that asks for analogue, with wording such as "analog type", "analogue indicator", "mechanical dial" or "dial gauge", rules out a family marked Digital, with the reason "has no analogue readout". A line that asks for digital, with "digital", "electronic", "LCD" or "LED display", rules out a family marked Analogue, with "has no digital readout". A family marked Both, or not marked, is never held back; nor is any family when the line asks for both or for neither. The ask is read from the line's description and the values stated or saved on it, and from a stated analogue or digital option; accessory, remark and note text is not read. A signal is not a readout: "4-20 mA analogue output", "analog signal", "digital output", "digital communication", and an output or communication field answered "Analog" or "Digital", ask for nothing, so a transmitter line with a 4-20 mA output keeps every family. "Pressure gauge: dial type", "electronic grade" and an LED lamp are other things and ask for nothing. A "not" or "no" after the word ("digital display not required", "LCD: No"), or "non" before it, cancels it. A family the customer names is checked the same way and, when held back, stays on the list as ruled out (R25). A family a reviewer picks keeps the reason as a caution. The marks are set once, when the feature is rolled out, on every family still **Not set**, so a family someone had cleared to Not set before that is marked again; after that, the page's choice stands. ## R25 — Every family the customer names is checked, not trusted, and stays on the list unless it cannot be offered If the named family fits, it is the pick, with up to four alternatives from its own category first. If it is ruled out, the five best alternatives are listed, the best as the suggestion, and the named family leads the Ruled out list with its reasons. A named family from another job than the line's own is still checked and shown, and a line with no category is Uncategorised: it lists only the families it names, fitting or ruled out. Names come from the line. Three families are never listed, even when named: a family that is not in use (R27), a companion-only family, and an accessory on any line but its own accessory line. On an accessory line (R27) the accessories the line names are listed, never a family of another category; once a person picks one, the picked family is the only one listed. When the line names none, what the line's own document states of it outside its row is used, such as its file name or the Type row of its specification; failing that, a family named in the enquiry's subject or body, but only when those names agree on one family. Either is judged, listed and picked like a named family. A reviewer's pick is kept beside the families named and does not replace them (R96), except on an accessory line, where the picked family is the only one listed. ## R26 — A line whose named families are all ruled out is a deviation If one of two named families fits, the line is confirmed or unverified. An Uncategorised line is never a deviation. A warning on a named family does not make a deviation: it stays the pick, with the warning shown. A family the customer asks for makes a deviation when it is ruled out wherever the enquiry names it: on the line, in the line's own document, or in the enquiry's subject or body. A name FlowOS only inferred never makes a deviation; it can make that family the pick within the line's own job, labelled inferred, but never brings in a family from another job. A type the customer names that covers several families, such as "bypass rotameter", makes a deviation the same way when none of those families fits: the one ruled out on fewest readings is shown first, with its reasons, and the alternatives come from its own category before any other, led by the ruled-out family's try-next families (R88). A family a reviewer picks that is outside the families asked for is a deviation as well (R96).