Armstrong Double Duty 6 Instruction Manual

Application
When there is modulating control on heat exchange equipment there is a possibility that the system will stall (no
longer be able to drain condensate). If only a steam trap is used condensate could flood the heat exchange
equipment causing corrosion, water hammer, and poor temperature control. The Double Duty™ has a steam trap
with an integral pump to prevent the system from stalling. If the condensate floods the body of the Double Duty™
and reaches its upper trip point high pressure steam will enter the body and push the condensate out. This prevents
condensate from accumulating in the heat exchange equipment.
Suggested Accessories
• Inlet and discharge check valves
• Gauge glass assembly for pump
• Gauge glass assembly for receiver
• Pressure gauge assembly pump body
• Pressure gauge assembly receiver
• Pressure gauge assembly motive steam
• Pressure gauge assembly discharge piping
• Pressure gauge assembly heat exchange equipment
• Receiver
Armstrong Double Duty™ 6
Steam Trap/Pump Combination
Installation and Maintenance
IB-119
This bulletin should be used by experienced personnel as a guide to the installation and maintenance of the Armstrong DD6 or DD6 package.
Selection or installation of equipment should always be accompanied by competent technical assistance. We encourage you to contact Armstrong
or its local representative if further information is required.
Steam
Maximum Operating Pressure 200 psi
Minimum Motive Differential 10 psi
Maximum Operating Temperature 400°F
Body Carbon Steel
Mechanism
Motive Fluid
Double Duty™ 6 Specifications
Model
Stainless Steel
Float Stainless Steel
Connections (condensate) 150# Flange
Inlet Check Valve Optional 1-1/2”
Discharge Check Valve Optional 1”
DD6
in mm
16-11/16 424
“C” 1-1/2 38
“D” 1 25
“E” 7/8 22
“F” 1-1/8 48
“G”
“B”
Double Duty™ 6 Physical Data
“A”
2-1/4 57
“H” 24 610
“J” 14 356
“K” 10-13/16 275
“L” 10 254
“M”
140 (64)
29 737
“N”
“O”
Weight lb (kg)
2-13/16 71
8 203
3-3/16 81
G
E
D
C
B
A1/2” NPT
Drain
1” 150#
Flange Outlet
1-1/2” 150#
Flange Inlet
K
J
H
1” NPT
Vent
.56 x 1.06
Slot (4 Places)
1/2” NPT
Motive
O
N
M
L
Springs Inconel X-750

2
Features
1. The trap body has an integral pump to prevent flooding of the heat exchange equipment. It uses steam motive
with no electricity or special mechanical seals required.
2. The pump mechanism is attached to the cap which can be removed from the body without taking it out of the
condensate line, and the steam trap mechanism can be accessed through the cap opening.
Operation
Operating as a trap (system pressure greater than back pressure)
As the condensate flows through the inlet check valve, the trap and pump floats become buoyant and rise with the
fluid level. The upward movement of the float causes the trap valve to open. If the system pressure is greater than
the back pressure the condensate will flow through the steam trap valve into the condensate return.
Operating as a pump (system pressure less than or equal to back pressure)
If the system pressure is less than the back pressure liquid floods the body. When the condensate reaches the
upper trip point of the pump mechanism the motive inlet valve opens and the vent valve closes. The open motive
valve allows the motive fluid to enter and pressurize the body. The pressure inside the body shuts the inlet check
valve and when it is greater than the back pressure pushes the water through the discharge check valve into the
condensate return line. The float lowers with the water level and when it reaches the lower pump trip point the
motive inlet valve closes and the vent valve opens. This relieves the pressure in the body and allows it to fill again.
Installation
1. Filling head: Install the DD6 below the equipment being drained. Fill head is the distance from the top of the cap
to the bottom of the receiver. The standard fill head for the DD6 is 6 inches.
2. Liquid reservoir: Liquid flowing from the heat exchange equipment must be stored during the pump discharge
cycle. A liquid reservoir or receiver should be installed above the unit to prevent flooding the equipment
3. Vent piping: The vent pipe must be pitched to self drain. The vent connection is 1” npt.
4. Replace any temporary plastic plugs with appropriate fittings.
5. Gauge glass connections are ½” npt and 10” center to center.
Steam Main
Condensate Main Condensate Main
Strainer w/
Blowdown
Safety
Relief
Valve
Modulating
Control Valve
Vacuum
Breaker
Coil
Thermostatic
Air Vent
Alternate
Equalizing Line
Vacuum
Breaker
Equalizing
Line
Reservoir
High Pressure
Steam
Fill Head
IB Steam
Trap
Thermostatic
Air Vent
D6469

Instructions
1. Before installing make sure the piping is clean and free of debris. When installing take care to not allow pipe tape
or similar items to enter the product.
* Debris can affect proper operation and performance
2. Check the condensate inlet, condensate outlet, motive inlet, and vent outlet ports before connecting piping.
3. The DD6 must be installed with the vent and motive vertical and the condensate inlet and outlet horizontal.
* The product will not function properly if not installed in the correct orientation
4. Connect pipes securely
5. When connecting pipes unions or flanges should be used close to the DD6 connections. This reduces the
amount of time needed for maintenance and repair.
6. Avoid water hammer. If water hammer is experienced it could injure personnel or damage the equipment.
7. Do not disassemble product. If the product is disassembled the function or performance of the unit could be
compromised.
8. Attach strainer with blow down valve on motive steam inlet.
9. Attach check valve on condensate inlet and discharge.
10.Attach the motive drip trap to the steam motive line.
11.Provide clearance for future maintenance.
Start-up procedures
Caution
Make sure all connections are secure before opening valves. Open valves slowly to reduce the chance of
water hammer
1. Open isolation valve(s) in condensate discharge.
2. Open isolation valve in equalizing line.
3. Open motive isolation valve. Confirm that the steam does not flow into the pump body or equalizing line by
checking pressure gauges.
4. Open the isolation valve on the thermostatic air vent.
5. Open the isolation valve on the condensate inlet.
6. The start-up is complete if the Double Duty Six performs trap operation or pump operation and is confirmed by
use of the gauge glasses and pressure gauges.
Maintenance and Inspection
Most failures occur because of debris in the piping.
Caution
Before starting any maintenance make sure the Double Duty™ 6 is completely isolated from the system.
Make sure the system is at atmospheric pressure
3

4
Trouble shooting
Problem Diagnosis Solution
Inlet isolation valve closed Open valve
Pump inlet and outlet switched
Motive inlet and vent switched
Discharge isolation valve closed
Equalizer line isolation valve closed
Motive pressure not adequate Adjust pressure
Motive inlet isolation valve closed Open valve
Motive strainer clogged Clean or replace
Air vent damaged Replace air vent
Motive pressure exceeds pump rating Adjust pressure
Outlet check valve installed backward Install check valve properly
Outlet check valve does not open Replace
Inlet check valve does not open Confirm lack of pressure in body
Inlet check valve is not completley closed Disassemble and clean check valve
Vent valve leaks Disassemble, clean and inspect - replace defective parts
Motive steam valve leaks Disassemble and replace inlet valve
Float damaged Disassemble and replace float
Motive steam valve leaks Disassemble and clean or replace
Mechanism not assembled properly Assemble so the motive valve is inserted in motive seat
Body gasket leaks Replace gasket
Plugs leak Remove, add thread sealer and reinstall
Open valve
Re-pipe
Condensate not
discharging
Motive steam
remains on
Steam leaks out of
body
Problem Diagnosis Solution

Mechanism Assembly
Adjustment Procedure
Armstrong Condensate Management Group, 221 Armstrong Blvd., Three Rivers, MI 49093 – USA Phone: [phone] Fax: [phone]
www.armstronginternational.com
IB-119 9/07