engineering & design manual for model ca combustion

ENGINEERING & DESIGN MANUAL

For

MODEL CA

Combustion Airflow Measuring Systems

Combustion Airflow Measuring Systems

11/97

MODEL CA - COMBUSTIONAIRFLOW MEASURING STATION

PAGE NO.

AIRFLOW PROCESSING .............................................................................................................. 1

CONSTRUCTION – STANDARD AND OPTIONAL ................................................................... 2

SUBMITTAL SHEETS

• Combustion Airflow (CA) Station - Rectangular ............................................................................. 3• Combustion Airflow (CA) Station - Rectangular w/Sensing Manifold Cleanout Plugs ................... 4• Combustion Airflow (CA) Station - Circular ................................................................................... 5• Combustion Airflow (CA) Station - Circular w/Sensing Manifold Cleanout Plugs ......................... 6• AUTO-purge III ................................................................................................................................. 7• AUTO-purge III - Installation Guide ................................................................................................. 8• AUTO-purge III - Sequence of Operations .......................................................................................... 9

OPERATION & MAINTENANCE ............................................................................................... 10

COMBUSTION AIRFLOW (CA) STATION - DESIGN & INSTALLATION GUIDE ......... 11

VELOCITY VS. RESISTANCE CHART .................................................................................... 12

PHOTOGRAPHS OF STATIONS

• Combustion Airflow (CA) Station - Circular .................................................................................. 13• Combustion Airflow (CA) Station - Rectangular w/Bellmouth ....................................................... 14

TABLE OF CONTENTS


Any physical structure placed across the flow of air in a ductwill impede the flow, the magnitude of which is a function ofthe size and shape of the structure and the quantity of airpassing through it. The Air Monitor air processing stationswere developed to produce a minimum of restriction to airflowby utilizing special open parallel cell honeycomb structureswith free areas of 96% or more. These Air Monitor airprocessing stations perform the basic conditioning functionsof straightening and equalizing the airflow.

The Model CA Combustion Airflow Measuring Station utilizesa 1" cell, hexagonal pattern, parallel cell, heavy duty weldedhoneycomb that functions as a combination air straightenerand equalizer. The 96%+ free area minimizes undesirablepressure drop on the airstream, while the 16 to 1 ratio of

peripheral area of each passage to its cross-sectional areaproduces a slight drag on the passing air. Since the drag orresistance to airflow varies with the square of the air velocity,the higher velocities are reduced while the lower velocities arepermitted to increase. In the illustration below, the arrowsrepresent the velocity magnitude after the air equalizingsection.

The process of air straightening simply removes the rotational,turbulent flow from the airstream, and directionalizes thatairflow while not significantly altering the velocity profile ofair passing through the material. Removal of rotational,multi-directional airflow is essential to the separation andaccurate measurement of the total and static pressures of theairstream.

AIRFLOW PROCESSING

1


STANDARD CONSTRUCTION

Casing. 3/16" carbon steel. Continuous welded seams. Casing depth is 12".

Flanges. Rectangular Stations: 2" wide, 90 degree formed flanges.Circular Stations: 3/16" x 2" barstock or 3/16" plate flanges, fusion welded.

Air Equalizer. 1" hexagonal, parallel cell equalizer-straightener 3" deep. .024" thick (24 ga) carbon steel.

Total Pressure Sensors and Manifold. All fabricated from Type 316 stainless steel, welded construction. Rectangular Stations: Multiple 5/64" I.D. impact sensors on ½" O.D. arms, connected to 1-1/8" O.D. averaging manifolds. Circular Stations: Multiple 5/64" I.D. impact sensors on multiple manifolds that are interconnected for signal averaging.

Manifold sizes on circular stations vary from ½" O.D. to 1" O.D. depending on unit diameter.

Static Pressure Sensors and Manifolds. All fabricated from Type 316 stainless steel, welded construction.

Rectangular and Circular Stations. Multiple 3/64" offset (Fechheimer) sensors on ¾" O.D. averaging manifolds.

Internal Signal Lines. ½" O.D., Type 316 stainless steel tubing welded to sensor manifolds and extended beyond casing exteriorvia ½" stainless steel compression fittings.

Finish. All internal and external black steel parts are provided without any special finish.

Packaging. Assembled station is crated in appropriate plywood and/or composition board over the entire air entering and leavingopenings. Entire unit is crated in dimensional lumber for protection during shipment and storage.

CONSTRUCTION

OPTIONAL CONSTRUCTION

Manual Cleanouts. Each total and static pressure manifold arm is extended through the casing wall and terminates in a femalepipe thread and plug. Removal of the plugs permits cleaning of the manifold interiors with compressed air and/or wire brushing.

AUTO-purge Control Panel. An automatic high pressure air purge system, with valving, delay relays, timer, etc., toautomatically activate a compressed air purge of the mass flow traverse probes at pre-determined time intervals. The systemshall isolate the mass flow transmitter input signal lines, lock the transmitter output signal at the last sensed value, and applyhigh volume, high pressure air to the probe manifold via a permanently connected piped air source to dislodge any particulatebuild-up at the sensor holes, as well as to discharge any accumulated particulate that may have collected in the probe manifold.To maximize the effectiveness of the automatic air purge, each manifold shall be individually purged (one at a time). All valvesand electronic circuitry are mounted in a NEMA 4 enclosure.

Protective Coatings. Two coats of oxide paint primer on casing interior, exterior, and/or air straightener surfaces.

Temperature Sensors. Single or multiple point (depends on unit size) thermocouple or RTD probes can be included in themeasuring station to provide temperature readout and/or thermal adjustment for mass flow. Type, size, and temperature rangeof the thermal probe to be customer or factory specified as required for each application.

NOTE

Alternate special construction requirements such as 1/4" or 3/8" casing thickness, large flanges,alternate materials of construction (Type 316 or 316L stainless steel, hastelloy, etc.) are available.

Contact the factory to discuss any unique or special construction needs.

2

SUBMITTAL SHEET

P.O. Box 6358 • Santa Rosa, CA 95406 • (707) 544-2706 • (707) 526-2825 Fax

SUB-Q005, Rev. 3 (7/99)

COMBUSTION AIRFLOW (CA) STATIONRECTANGULAR


Casing. 3/16" carbon steel, continuous welded.Flanges. 2" wide, 3/16" carbon steel formed 90º.Air Straightener. 1" hexagonal cell, 3" deep, 0.022" thick, carbon steel.Total Pressure (T.P.) Manifolds. Type 316 stainless steel.Static Pressure (S.P.) Manifolds. Type 316 stainless steel.Signal Connection Fittings. 1/2" FPT, 316 stainless steel. (Units with more than 24 T.P. sensors require 3/4" FPT.)


� 1/4" carbon steel casing and formed flanges. � Casing and flanges painted with iron oxide primer.� Special flanges. � Temperature sensor and transmitter capable of 4-20mA output.� Factory drilled bolt holes. � Bellmouth on air intake side.

DIMENSIONAL SPECIFICATIONS

3.2.4

SUBMITTAL SHEET


SUB-Q006, Rev. 3 (7/99)

COMBUSTION AIRFLOW (CA) STATIONRECTANGULAR with Sensing Manifold Cleanout (C.O.) Plugs


Casing. 3/16" carbon steel, continuous welded.Flanges. 2" wide, 3/16" carbon steel formed 90º.Air Straightener. 1" hexagonal cell, 3" deep, 0.022" thick, carbon steel.Total Pressure (T.P.) Manifolds. Type 316 stainless steel.Static Pressure (S.P.) Manifolds. Type 316 stainless steel.Signal Connection Fittings. 1/2" FPT, 316 stainless steel. (Units with more than 24 T.P. sensors require 3/4" FPT.)Manual Cleanout (C.O.) Plugs. 3/8" FPT, carbon steel.


� 1/4" carbon steel casing and formed flanges. � Casing and flanges painted with iron oxide primer.� Special flanges. � Temperature sensor and transmitter capable of 4-20mA output.� Factory drilled bolt holes. � Bellmouth on air intake side.


3.4.4

SUBMITTAL SHEET


SUB-Q008, Rev. 3 (7/99)

COMBUSTION AIRFLOW (CA) STATIONCIRCULAR with Sensing Manifold Cleanout (C.O.) Plugs


Casing. 3/16" carbon steel, continuous welded.Flanges. 2" wide, 3/16" carbon steel, welded to casing.Air Straightener. 1" hexagonal cell, 3" deep, 0.022" thick, carbon steel.Total Pressure (T.P.) Manifolds. Type 316 stainless steel.Static Pressure (S.P.) Manifolds. Type 316 stainless steel.Signal Connection Fittings. 1/2" FPT, 316 stainless steel. (with more than 24 T.P. sensors require 3/4" FPT.)Manual Cleanout (C.O.) Plugs. 3/8" FPT, carbon steel.


� ¼" carbon steel casing and plate/bar flanges. � Casing and flanges painted with iron oxide primer.� Special flanges. � Temperature sensor and transmitter capable of 4-20mA output.� Factory drilled bolt holes. � Bellmouth on air intake side.


3.4.2

SUBMITTAL SHEET


SUB-Q007, Rev. 3 (7/99)

COMBUSTION AIRFLOW (CA) STATIONCIRCULAR


Casing. 3/16" carbon steel, continuous welded.Flanges. 2" wide, 3/16" carbon steel, welded to casing.Air Straightener. 1" hexagonal cell, 3" deep, 0.022" thick, carbon steel.Total Pressure (T.P.) Manifolds. Type 316 stainless steel.Static Pressure (S.P.) Manifolds. Type 316 stainless steel.Signal Connection Fittings. 1/2" FPT, 316 stainless steel. (Units with more than 24 T.P. sensors require 3/4" FPT.)


� 1/4" carbon steel casing and plate/bar flanges. � Casing and flanges painted with iron oxide primer.� Special flanges. � Temperature sensor and transmitter capable of 4-20mA output.� Factory drilled bolt holes. � Bellmouth on air intake side.


3.2.2

SUBMITTAL SHEET

P.O. Box 6358 • Santa Rosa, CA 95406 • (707) 544-2706 • (707) 526-2825 Fax • www.airmonitor.com

SUB-M004, Rev. 6 (7/99)

AUTO-purge III


� Brass and Copper Construction All wetted tubing, fittings, and valves constructed of copper and/or brass.Enclosure is NEMA 4 painted steel.External connection fittings are stainless steel FPT.

� Stainless Steel Construction All wetted tubing, fittings, and valves are constructed of 316 stainless steel.Enclosure is NEMA 4 painted steel.External connection fittings are stainless steel FPT.


� NEMA 4X Stainless Steel Enclosure SV-1 / SV-2� Enclosure Heater. Requires 120VAC power supply. � 24VAC, 36VA� Vortex Cooler. Requires 80-100 psi air supply **. � 24VDC, 36VA� Continuous Enclosure Purge **. � 120VAC, 36VA** These options require a 24 X 24 enclosure.


8.28.2

SUBMITTAL SHEET


SUB-M009, Rev. 5 (8/01)

AUTO-purge IIIINSTALLATION GUIDE

Air Requirement.

80 to 125 psig at 100 CFM, oil and dirt free. 1 to 24 purge cycles per day, with a field selectable duration between 30 and 120seconds during which compressed air is released.

Line Size from AUTO-purge Panel to Flow Measuring Station or Probes.

Distance from AUTO-purge panelto flow measuring station air probe. Tube Size.

< 25' 1/2" S.S. tube25' - 50' 3/4" S.S. tube

> 50' 1.0" S.S. tube

Accumulator Tank (strongly recommended).Requires coalescing filter, pressure regulator, and check valve at the tank inlet.

120 gallons - All CA stations.120 gallons - Multiple VOLU-probes having a combined length greater than 10'.80 gallons - One or more VOLU-probes having a combined length less than 10'.

Line from Accumulator Tank to AUTO-purge Panel.

25' maximum length, ½" pipe (minimum). Recommend locating accumulator tank as close as possible to AUTO-purge panel.

Electrical Power Requirement.

None when used with an Air Monitor transmitter. (NOTE: This adds 36VA to the transmitter's power requirement.)24VAC, 36VA when not initiated by an Air Monitor transmitter.120VAC, 10 amp when an optional enclosure heater is installed.

Ambient Temperature.

40ºF-140ºF. For ranges above or below this ambient temperature, use of panel heater and/or cooler is required.

Purge Frequency.

Once/day minimum, once/hour maximum.

8.30.2

SUBMITTAL SHEET


SUB-M013, Rev. 7 (8/99)

AUTO-purge IIISEQUENCE OF OPERATIONS

IDENTIFICATION CODE

V-1,3 Pneumatically Piloted, 5-Way Valve, Static (low) PressureV-2,4 Pneumatically Piloted, 5-Way Valve, Total (high) PressureSV-1 Solenoid Operated 5-Way ValveSV-2 Solenoid Operated 3-Way ValveHV-1 Supply Air Shut Off ValvePI-1, 2 Gauge, Supply Air Pressure, 0-160 psigTB-2 Terminal Block, Purge Start Command from TransmitterPRV-1/FLTR-1 Pressure Regulator / Filter Assembly

SEQUENCE OF OPERATIONS

Automatic line purging interrupts airflow signal transmission atregular field selectable intervals and purges the station sensinglines with up to 125 psig air for short periods. This periodicpurging assists in maintaining the sensing orifices of the totaland static pressure manifolds in a clean, unobstructed condition.

A selectable timing sequence provided by the smart transmitteractivates solenoid valves (SV-1 and SV-2) which shuttles thetransmitter isolation valves (V3 and V4) and purge valves (V1and V2). A simultaneous output signal hold corresponding to thelast measured input is initiated by the transmitter and maintaineduntil the purge cycle is complete.

When valve V1/V3 and V2/V4 operate, the velocity pressure signallines (C and D) to the flow transmitter are isolated, and highpressure purge air AS1 is routed to the station (probes) sensinglines (A and B). The high pressure purge air cleans the flowsensing orifices of the flow station (probes) during the purgeduration.

At the end of the purge cycle the transmitter withdraws its purgesignal, de-energizing SV-1 and SV-2 and causing valves V3/V4and V1/V2 to reset after a short time delay to their normalposition, thereby reconnecting the process sensing lines to thetransmitter. After a short timed interval the transmitter signal holdis terminated and on-line signal processing resumes.

SCHEMATIC

8.32.2

SYSTEM DIAGRAMMATIC


In addition to being fabricated from durable, corrosion resistant materials, the Model CA Combustion Airflow Measuring Stationhas no moving components or parts that require periodic replacement or calibration. As such, the operation and maintenanceprocedures required for continued operation of the station are extremely limited.

The operating life of the Model CA Combustion Airflow Measuring Station is anticipated to be that of the operating life of theboiler or power facility.

OPERATION & MAINTENANCE

• The Model CA Combustion Airflow Measuring Station hasa built-in air processing section (straightening andequalizing). This enables the station to be installed withoutthe long runs of straight ductwork upstream and downstreamof the station location (as required with the airfoils, otherprobe types, etc.). On new installations, this feature canpossibly reduce ductwork requirements by permitting thedesign to be condensed. Refer to to obtain minimumrequirements for installation of the Model CA CombustionAirflow Measuring Stations.

• The air processing section also assures that the automaticaveraging Pitot tube section will sense the duct flowaccurately, within 2 to 3% of the actual flow passing throughthe station and duct. Having no moving parts, the accuracyof the station is basic. It requires no field testing, verification,or periodic calibration.

• The pressure drop, due to the presence of the station in theduct, is extremely low (refer to Page 1). At 2,000 fpm, theresistance to airflow of the Model CA Combustion AirflowMeasuring Station at 70 degrees is only 0.12 IN w.c. Thisis a small fraction of that of airfoils, orifices, etc., and ifproperly correlated back to the fan static requirements andselection, a considerable reduction in fan horsepower andsystem operating static can be made.

• The presence of the air straightener/equalizer section alsobenefits the air pattern downstream of the station. By itselimination of rotational, turbulent airflow it can be of adecided benefit to the air distribution pattern. In applicationswhich are adjacent to the wind boxes (or ductwork take-offto them), this can be a decided help.

• The multiple total and static pressure sensors of the ModelCA Combustion Airflow Measuring Station preclude theunlikely possibility of multiple sensors plugging due toairborne contaminants in the flow stream. However, shouldsome or many of the openings become blocked, the stationwill continue to average the remaining sensors to produce ausable and highly repeatable flow signal.

• In particularly dirty applications or as a result of long termcontamination build-up, one or more of the individualsensors may become plugged. To correct for this problemwithout requiring internal cleaning or sensor manifoldremoval, all Model CA Combustion Airflow MeasuringStations can be equipped with sensor manifold cleanoutports accessible from outside the casing.

• Manual cleaning can be accomplished by removing the endcaps on the sensing manifold(s) and cleaning them by meansof compressed air. Care must be exercised during manualcleaning with the fan system operating since accumulatedcontamination will tend to blow out of the ports of unitsinstalled on the pressure side of the fan.

• Automatic cleaning can be accomplished using the AUTO-purge system, which consists of a series of valves, aprogrammable controller, and an interface with the signaltransmitter/controller contained in a NEMA 4 enclosure. Asource of high capacity 100 psi compressed air must beavailable at the installation site. The purge frequency isdetermined by the contamination level of the operatingsystem and is field set for a frequency range of once per dayto once per month.

10

SUBMITTAL SHEET


SUB-H014, Rev. 3 (3/97)

COMBUSTION AIR STATIONSMINIMUM INSTALLATION REQUIREMENTS

INSTALLATION CONSIDERATIONS. Installation factors to be considered when applying the Combustion Air Station are as follows:

Turbulent Airflow. The unique use of honeycomb airflow straightener in the Combustion Air Station will permit accurate flow measure-ment in the presence of moderate air turbulence. The distances from air turbulence producing fitt ings, transitions, etc.,shown below in the Minimum Requirements for Installation, are required to assure accurate Combustion Air Station operation.

Airborne Contaminants. Industrial applications containing airborne contaminants may require periodic manual or automatic cleaningusing compressed air applied via the signal fittings, and/or physical cleaning.

Direction of Airflow. The Combustion Air Stations will function only with the airflow passing through the air straightener section prior toentering the total and static pressure sensing section. To prevent improper installation, each Combustion Air Station is marked withan arrow indicating the required direction of airflow.

MINIMUM REQUIREMENTS FOR INSTALLATION. Note: Combustion Air Station locations shown are NOT ideal. They indicatethe minimum clearance required from air turbulence producing sources. Wherever possible, the Combustion Air Station should beinstalled where greater runs of straight duct (or clearances) than shown exist.

1X 1.5XX2

ROUND SWEEPELBOW

90º VANEDELBOW

2.5XX2

CENTRIFUGAL FANDISCHARGE

3X

FANS DAMPERS

TAKEOFFS

2.5X

1X

X2

2.5X

1.5XX2

SWEEP ELBOW90º UNVANED ELBOW

X24X

ELBOWS

DUCT TRANSITIONSX2

α

α

X2

α

α

α

α

α

α

α

X2

X2

α

α

α

TRANSITION ANGLE: < -15º TRANSITION ANGLE: < -15º TRANSITION ANGLE: < -15º TRANSITION ANGLE: < -15º

( )Rectangular Duct: x = Circular Duct: x = Duct Diameter

2 H x W

H + W

3.6.1

MODEL CA - COMBUSTIONAIRFLOW MEASURING STATION CHART

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AIR VELOCITY IN FEET PER MINUTE

12


Model CA Combustion Airflow Measuring Station

PHOTOGRAPHS

13

P.O. Box 6358 • Santa Rosa, CA 95406 • TEL 800-AIRFLOW • Fax 707-526-9970 • www.airmonitor.com

engineering & design manual for model ca combustion

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