Fume hood sash, walk-in and external (FhSash13)

Overview

The application function "Fume hood sash 13, walk-in and external" (FhSash13) is used to calculate the face area of a walk-in or floor mounted fume hood with two sashes that move in the same vertical track.

Main features:

Face area calculation
Face area valid signal

Function

	Command or request (or related)
	Notification of condition or status, or availability
	Device mode
	Interlock (internal signal, not a BACnet object; see Interlocks section for additional information)

Face area calculation:

The sashes in this type of fume hood can overlap and block the same area of the opening. The calculation for the open face area must account for any overlap of the sashes.

Face area is a calculated value that uses the following:

FhSash1Pos – Sash position from the sash sensor, analog input value.
FhSash2Pos – Sash position from sash sensor 2, analog input value.

FhExtFaceArea – External face area, analog input value.
SashTckHgt – The height of the sash track, analog configuration extension item.

HgtVrtSash1 – The height of vertical sash 1, analog configuration extension item.
HgtVrtSash2 – The height of vertical sash 2, analog configuration extension item.
WdtVrtSash – The width of the vertical sash, analog configuration extension item.

HgtBypOpn – Height of bypass opening, analog configuration extension item.
BypOpnUrstd – Unrestricted bypass opening, analog configuration extension item.
TotAreaFixOpn – Total area of fixed openings, analog configuration extension item.
ExtFaceArea – External face area is used, binary configuration extension item.
AreaSenFail – Area on sensor failure, analog configuration extension item.
FhFaceArea – Fume hood face area, analog calculated value, for monitoring only.

Face area valid signal: The FaceAreaVld output is used by other modules to determine if the general fume hood failure alarm should be active and to set other objects to valid.

The FaceAreaVld signal is a combination of valid signals from the sash 1 position sensor and external face area. ExtFaceArea is used to determine if there is an active external face area device.

The output will only be ON and FhFaceArea will only be set valid when:

sash 1 position sensor, sash 2 position sensor and external face area are valid, and external face area is active.

sash 1 position sensor and sash 2 position sensor are valid, and external face area is not active.

Note
Sash sensor(s) must be calibrated. See Sash calibration and verification in Technical principals for more information.

Feature configuration

Feature selections for "Room HVAC coordination" are accessed via the Application configuration task in the Configuration component.

Feature (AF)	Feature description	Ref.
Trend for fume hood face area	None/Active	☑

Configuration

Parameters

Description	Parameter	Default value
External face area ▶ Set to Yes if a Sash Open Area Module is connected on SCOM. 0:No 1:Yes	ExtFaceArea	0:No
Sash track height ▶ Fully open the sashes. Measure the height of the vertical height in inches (cm). Set SashTckHgt to this value.	SashTckHgt	0 [cm] 0.0 [in]
Height of vertical sash 1 ▶ Measure the height of vertical sash 1 in inches (cm). Set HgtVrtSash1 to this value. Measure the height of vertical sash 2 in inches (cm). Set ‘Height of vertical sash 2’ (HgttVrtSash2) to this value.	HgtVrtSash1	0 [cm] 0.0 [in]
Height of vertical sash 2 ▶ Measure the height of vertical sash 2 in inches (cm). Set ‘Height of vertical sash 2’ (HgttVrtSash2) to this value.	HgtVrtSash2	0 [cm] 0.0 [in]
Width of vertical sash ▶ Measure the width of the sash opening in inches (cm). Set WdtVrtSash to this value.	WdtVrtSash	0 [cm] 0.0 [in]
Height of bypass opening ▶ Open the sash until the top edge of the sash is aligned with the top edge of the bypass area, closing the bypass area. Measure the height of the sash opening in inches (cm). Set HgtBypOpn to this value.	HgtBypOpn	0 [cm] 0.0 [in]
Unrestricted bypass opening ▶ If there is no restriction on the bypass, leave BypOpnUrstd at the default (100%). If the bypass area has an airflow restrictor covering the open area, such as a perforated grille or louvers, estimate the open percentage of the bypass area. Set BypOpnUrstd to the appropriate value.	BypOpnUrstd	100 [%]
Total area of fixed openings ▶ Measure the fixed area of the fume hood in square feet (m²). Any fume hood leakage must be accounted for in this measurement. Set TotAreaFixOpn to this value.	TotAreaFixOpn	0 [m²] 0.0 [ft²]
Area on sensor failure ▶ Set AreaSenFail to the value that will be used as the fume hood face area in the event of a sash sensor failure.	AreaSenFail	0.5 [m²] 5.38 [ft²]
Length unit ▶ Defined by selected engineering unit – do not change.	LngtUnit	[cm] [in]
Area unit ▶ Defined by selected engineering unit – do not change.	AreaUnit	[m²] [ft²]

Interface

Interface	Description	Type	Ref.	Owned by
FhExtFaceArea	Fume hood external face area	AI	◉	Room segment / Field device
FhSash1Pos	Fume hood sash 1 position	AI	◉	Room segment / Field device
FhSash2Pos	Fume hood sash 2 position	AI	◉	Room segment / Field device
FhFaceArea	Fume hood face area	ACalcVal	●	-
TrndFhFaceArea	Trend for fume hood face area	FtrSel	●	-

Engineering and commissioning

Optional.