Midco HMA-2A Service Manual

Installation and Service Instructions

MADE in the USA

HMA 2 &
HMA 2A

Direct-Fired Gas Burners

The Blue Flame Series

DIRECT FIRED MAKE-UP AIR BURNERS are used in
industrial and commercial applications to maintain the
desired environmental temperatures required by critical
processes i.e. health purposes, production systems,
quality control, comfort and loss prevention where it
is necessary or required to exhaust large amounts of
conditioned air.

Make-up Air Systems used as stand alone heating
systems or operating in combination with central heating
plants systems can be cost effective in three ways: 1)
reducing the initial expenditures, 2) tempering incoming
air which may extend the life of expensive central heating
plants and 3) reducing excessive equipment cycling or
premature component failures due to increased heating
demands.

Our innovative two stage combustion burner is not just a
modifi cation or improvement of the old, but a completely
new approach to direct-fi red combustion. The two-stage
combustion improves control of the fl ame process, meets
or exceeds the new ANSI Standards while outperforming
the competition. By incorporating two separate fl ames
within the burner combustion zone, the fl ame is more
stable, shorter and cleaner, permitting the reduction of
emissions levels and allowing for higher temperature rise
and higher tolerance to varying conditions when placed in
the profi le opening.

Features and Benefi ts

Reduced NO2 and CO Emissions: Lower emissions
levels that pass the ANSI Z83.4, Z83.18 and Z83.25 standards.

Higher Temperature Rise: The two stage combustion
process lowers NO
temperature rise.

Increased Capacity: Up to 750,000 BTU’S per foot. (Higher
BTU levels can be achieved if ANSI Z83 Standards for CO and
NO

emissions are not of a concern. Process heaters can fi re

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up to 1,000,000 BTU’S a foot or more.)

Increased Differential Pressure Drop and Higher Velocities:
HMA 2 & 2A burners can operate as low as 0.05″ to 1.4″ W.C.
differential pressure range or in air velocity as low as 800 fpm to
4000 fpm.

Flame Stability: Two stage combustion provides better fl ame
stability and emission control, allowing for a shorter fl ame and
easier profi le confi guration.

Reduced Inventory Costs - HMA 2A: Single burner casting
can be fi red with natural, propane or butane gas
burner inventory.

Reduced Shipping Costs: A smaller, lighter casting than the
competition’s, can lower your freight costs.

Turndown: 30-1 turndown can be achieved with proper
modulating controls and valves. (Higher turndown possible
depending on equipment design.)

emissions which is the limiting factor in

2

1

, reducing

Midco® International Inc.
4140 West Victoria Street
Chicago, Illinois 60646
toll free 866.705.0514
tel [phone]
fax [phone]
web www.midcointernational.com
e-mail [e-mail]

Emission performance is application specifi c and may vary.

1

Consult Midco for applications using butane fuels.

Quality Designed for Proven Performance

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8471 34

Printed in USA

Specifi cations

Specifi cations

*Firing Rate .............................................................. Up to 750,000 Btu/hr/ft

750,000+ Contact Midco
Burner Manifold Pressure

Natural Gas ................................................. 4.2 to 8 inch W.C.

Propane Gas .............................................. 1.6 to 3 inch W.C.

Pilot Capacity ............................................................ 12,000 Btu/hr

Pilot Manifold Gas Pressure

Natural Gas ................................................. 3.5 inch W.C.

Propane Gas .............................................. 2.0 inch W.C. **

Pressure Drop Across the Burner ............................ 0.05 to 1.4 inch W.C.

Air Velocity Across the Burner ................................... 800 to 4,000 FPM

Burner Turn-down Ratio ........................................... 30 to 1 (based on Btu / ft)

Flame Length ....................See page 5 for fl ame length Chart 5, and Tables 2 & 3

* Firing rate is dependent on the pressure across the burner. Please see the included
charts for recommended burner sizing.

** Using a natural gas pilot on propane.

Cast Iron (CI) Aluminum (AL)

*** Burner Confi gurations HMA 2 HMA 2A HMA 2 HMA 2A

2″ Straight Section (2A only) - - - 1020810

6″ Straight Section 1050700 1050710 1050800 1050810

6″ Straight Section with Back Inlet 1230700 1230710 1230800 1230810

12″ Straight Section 1010700 1010710 1010800 1010810

12″ Straight Section with Back Inlet 1060700 1060710 1060800 1060810

Elbow Section 1070700 1070710 1070800 1070810

Tee Section 1080700 1080710 1080800 1080810

**** Pilot Confi gurations Part # Natural # Propane #

Brute Pilot Spark Rod and Flame Rod 1190850 1190950

Brute Pilot Spark Rod and UV Mount 1200350 1200450

Brute Pilot Spark Rod 1342-03

Brute Pilot Flame Rod 1360-03

(Direct) Spark Rod and Flame Rod 1190800 1190900

(Direct) Spark Rod and UV Scanner Mount 1200300 1200400

Remote Flame Rod 1220800

Remote UV 1240800

Pilot with Spark Rod only 1210800 1210900

Flame Rod

Spark Rod (Direct Spark) 1342-06

*** See Page 14, Figure 6 for burner confi guration reference.

**** See Page 15, Figure 7 for pilot confi guration reference

(Direct Spark, Std + Brute)1360-03

Table 1 - Burner and Pilot Confi gurations

Midco International Inc. reserves the right to change the construction or confi guration of its products at any time.
All information is based on laboratory testing. Different unit size and/or confi gurations may affect data.

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Midco International Inc.

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HMA 2 & HMA 2A Burner Performance

Burner Performance

5.0

4.0

CO Emission

3.0

2.0

CO (PPM)

1.0

0.0
0

20

40 60 80 100 120

Temperature Rise*

750,000 Btu/hr/ft at 1.1" W.C. pressure drop across the burner

5.0

4.0

CO Emission

3.0

2.0

CO (PPM)

1.0

0.0

0 20406080100

Temperature Rise*

550,000 Btu/hr/ft at 0.6" W.C. pressure drop across the burner

5.0

4.0

120

0.5

NO Emission

2

0 20406080100120

0.4

0.3

0.2

0.1

0.0

Temperature Rise*

750,000 Btu/hr/ft at 1.1" W.C. pressure drop across the burner

0.5

NO Emission

2

0 20406080100120

0.4

0.3

0.2

0.1

0.0

Temperature Rise*

550,000 Btu/hr/ft at 0.6" W.C. pressure drop across the burner

0.5

NO Emission

2

0.4

2

NO (PPM)

2

NO (PPM)

3.0

2.0

CO (PPM)

1.0

0.0
0 20406080100

CO Emission

120

Temperature Rise*

350,000 Btu/hr/ft at 0.35" W.C. pressure drop across the burner

100

90

80

2

70

60

50

40

30

x

20

NO (PPM at 3% O )

10

0.0
0

NO Emissions Profile

x

100000 200000 300000 400000 500000 600000

Heat Input (Btu/hr/ft)

0.3

0.2

0.1

0

20

40 60 80 100 120

0.0

Temperature Rise*

350,000 Btu/hr/ft at 0.35" W.C. pressure drop across the burner

.45 Delta P

.64 Delta P

.85 Delta P

* For higher temperature rise contact
Midco Engineering Department.

NOTE: Emission performance is
application specific and will vary

2

NO (PPM)

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Chart 1 - CO and NO2 Emissions Data

Midco International Inc.

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HMA 2 & HMA 2A Burner Performance

Burner Performance
Continued

800,000

700,000

600,000

BTU/hr/ft

500,000

400,000

300,000

9.0

8.0

7.0

6.0

5.0

4.0

(Manifold)

3.0

Natural Gas

Propane Gas

0.20 0.40 0.60 0.80 1.00 1.20

Pressure Drop across the Burner ("W.C.)

Chart 2- BTU’s verses Pressure Drop

Natural Gas

2.0

Fuel Gas Pressure ("W.C.)

1.0

0.0
100,000 200,000 300,000 400,000 500,000 600,000 700,000

Propane Gas

BTU/hr/ft

Chart 3- BTU’s verses Gas Pressure ( ″W.C.)

4,500

4,000

3,500

3,000

2,500

2,000

Profile Velocity (SFPM)

1,500

1,000

0.20 0.40 0.60 0.80 1.00 1.20

Pressure Across the Burner ("W.C.)

Chart 4 - Pressure Across the Burner verses Profi le Velocity

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Midco International Inc.

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Installation

- Velocity and pressure drop fi gures shown in Table 2 apply to standard design conditions.
However, these conditions apply only when air enters the heater at 70° and requires little or no heat.
In practice with the burner operating, these fi gures will vary, especially with inlet air at the minimum
design temperature. This is because the blower handles a constant volume of air regardless
of its temperature. When the air is heated expansion takes place ahead of the blower and just
downstream of the burner. It follows therefore that when the air is being heated a lesser volume
enters the heater, causing a reduction, both in velocity and pressure drop at the burner. Table
2 shows the variation for minimum temperature air entry and with full input to the burner. Flame
lengths given in Table 2 and Chart 5 apply to conditions shown in Table 2.

Air fl ow at burner Approximate length of fl ame
based on 70° (std) Burner Capacity (per foot) projecting beyond end of
blower rating Natural & Propane Gas burner and profi le plate *
Design
Design Pressure Max. Min.
velocity drop capacity capacity Turn 550,000 650,000 750,000
FPM ″ W.C Btu/Hr Btu/Hr Down per ft per ft per ft
3200 .7″ 550,000 19,000 29:1 13″ 16″ 20″
2850
(ideal)
2500 .45″ 550,000 17,000 32:1 17″ 20″ 24″

Reduce capacity 4% per each 1000 ft altitude over 2000 ft.

.55″ 550,000 18,000 30:1 15″ 19″ 22″

Table 2 - Design Data for Pull-Thru System

* Flame lengths are given to the end of the main mass of fl ame, excluding any isolated
wisps or fl ashes, and for normal operations ie. with cold inlet air (design minimum)

Air Flow Variations
Due to Heating in a

Pull-Thru System

Velocity Pressure Air Actual cold Actual cold
at burner drop at temp. air velocity air pressure

(from Table 1) burner rise at burner drop at burner

3200 fpm .7″ W.C.

100° 2600 fpm .46″ W.C.

2850 fpm .55″ W.C.

100° 2300 fpm .36″ W.C.

2500 fpm .45″ W.C.

100° 2000 fpm .29″ W.C.

75° 2750 fpm .52″ W.C.

75° 2450 fpm .41″ W.C.

75° 2150 fpm .33″ W.C.

Table 3 - Air Flow Variations for Pull-Thru System

EXAMPLE: A heater rated for 100° rise, 70° outlet temperature at a design velocity of 2850 fpm
and a design pressure drop of .55″ W.C., will in actual operation pass 2300 fpm over
the burner with a .36″ W.C. drop when air enters at -30°.

HMA 2 & HMA 2A Flame Length

35

30

750,000 Btu/ft

650,000 Btu/ft

25

550,000 Btu/ft

20

15

10

Flame Length ( inches )

5

0

1.20.2 0.4 0.6 0.8 10

Pressure Drop ( " W.C.)

Chart 5 - HMA 2 & 2A Flame Length

HMA 2 & HMA 2A fl ame length as a function of pressure drop and fi ring rate applies to push and pull
through systems using 100% fresh standard air.

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Midco International Inc.

5

Installation

Profi le Setup

1. Required BTU:
BTU/hr = Blower SCFM x Desired Temp. Rise x 1.08 / .92

2. Required Burner Length:
Feet of burner = [Required BTU/hr]÷[Burner Firing Rate (BTU/hr/ft)]
The Burner Firing Rate should correspond to the pressure drop across the burner
shown in Chart 2.

3. Required Profi le Area:
Total Burner Area = Number of burner sections x burner area

(Burner Section) Burner Area
2 inch 0.11 sq. ft.
6 inch 0.32 sq. ft.
12 inch 0.65 sq. ft.
T Section 0.77 sq. ft.
Ell Section 0.65 sq. ft.

Net Profi le Area = Rated Fan (SCFM) ÷ Profi le Velocity (SFPM)
The Profi le Velocity can be determined from the following:

Profile Velocity

∆P is the pressure drop across the burner

Profi le Area = Net Profi le Area + Total Burner Area
___________________________________

=

945

PΔ

0750

.

Profi le Setup Example

Sizing the burner and the corresponding profi le for a 5,000 SCFM and a 115 degrees

temperature rise.

1. Required BTU:

BTU/hr = Blower SCFM x Desired Temp. Rise x 1.08 / .92

BTU/hr =5,000 (SCFM) x 115 (∆T) x1.08 / .92 = 675,000 BTU/hr

2. Required Burner Length:

Feet of burner = [Required BTU/hr]÷[Burner Firing Rate (BTU/hr/ft)]

To determine the optimum burner length we can choose from a combination of 12
inch or 6 inch burner sections referring to Table 1. We can either fi re the burner
at a rate of 675,000 BTU/hr per ft, or we can fi re the burner at 450,000 BTU/hr per ft
(1.5 feet of burner). Refer to Chart 3 for the fuel pressures requirements at different
fi ring rates.

3. Required Profi le Area:

Total Burner Area = Number of burner sections x burner area

(Burner Section) Burner Area
2 inch 0.11 sq. ft.
6 inch 0.32 sq. ft.
12 inch 0.65 sq. ft.
T Section 0.77 sq. ft.
Ell Section 0.65 sq. ft.

Total Burner Area = 1.0 (ft) x 0.65 = 0.650 ft
Or
Total Burner Area = 1.5 (ft) x 0.65 = 0.975 ft

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Midco International Inc.

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