The Armstrong EDD-4 (Double Duty® 4) steam trap and pump combination offers a low-profile solution for draining heat exchangers in various applications. It provides the versatility of combining a pump within a steam trap to aid in condensate drainage from a heat exchanger under all operating conditions, preventing system stall and flooding.

Features

• Economical, non-electric operation: Uses steam motive with no electricity required.
• Low-maintenance operation: No leaking seals, impeller, or motor problems. No NPSH issues.
• Space-saving size: Low-profile body fits in tight spaces while allowing minimal fill head.
• Ductile iron durability: Rugged construction material ensures a long service life.
• Efficiency: A closed loop means no motive or flash steam is lost. All valuable heat is captured and returned to the system.
• Safety: Intrinsically safe. The trap/pump can be used in pits or sumps without fear of electrocution or circuit breaker defaults.

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 in this case, condensate could flood the heat exchange equipment causing corrosion, water hammer, and poor temperature control.

The EDD-4 features a steam trap with an integral pump to prevent the system from stalling. If the condensate floods the body of the EDD-4 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.

Operation

Operating as a Trap (System pressure greater than back pressure)

As the condensate flows through the inlet check valve, the float becomes buoyant and rises 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 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 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.

Materials and Specifications

Component	Material
Body	Ductile iron
Mechanism	All stainless steel
Springs	304 Stainless steel
Float	All stainless steel

Maximum Operating Conditions:

• Maximum allowable pressure: 72 psig @ 320°F (5 bar @ 160°C)
• Maximum operating pressure: 72 psig @ 320°F (5 bar @ 160°C)
• Minimum Motive Differential: 5 psi

Dimensions and Weights

Dimension	in	mm
A	11-3/16	284
B	10-13/16	274
C	1	25
D	8	203
E	2-7/16	61
F	1	25
G	3	76
H	6-1/8	155
J	1-5/8	41
K	5-1/2	140
L	9-15/16	251
Weight	37 lb	17 kg

Capacities

Pump Capacities

Motive (bar)	Back Pressure (bar)	Capacity (kg/hr)
1	0.34	100
1.7	0.34	136
3.5	0.34	158
4.5	0.34	159
1.7	1	100
3.5	1	156
4.5	1	158
2.5	1.7	100
3.5	1.7	147
4.5	1.7	158
3.5	3	100
4	3	136
4.5	3	152
4.5	4	100

Note: Published capacities are based on the use of external check valves supplied by Armstrong. Fill head measured from drain point to top of pump case.

Trap Capacities

Differential Pressure (bar)	Capacity (kg/hr)
0.34	610
0.7	900
1.4	1300
2.1	1550
3	1745
3.4	1850
4.1	1925
4.8	2000

Capacity Conversion Factors for Other Filling Heads

Filling Head (mm)	0	150	305
Factor	0.65	1.0	1.10

Installation

WARNING

Before installing, make sure the piping is clean and free of debris. Debris can affect proper operation and performance. Avoid water hammer, which could injure personnel or damage the equipment.

1. Check the condensate inlet, condensate outlet, motive inlet, and vent outlet ports before connecting piping.
2. The EDD-4 must be installed with the vent vertical and the condensate inlet and outlet horizontal. The product will not function properly if not installed in the correct orientation.
3. When connecting pipes, unions should be used close to the connections to reduce maintenance time.
4. Attach a strainer with a blowdown valve on the motive steam inlet.
5. Attach a check valve on the condensate discharge.

Maintenance and Troubleshooting

Most failures occur because of debris in the piping. Perform a periodic inspection once a year by isolating the unit, flowing water into the top connection, and confirming a clicking noise when the mechanism trips.

Problem	Diagnosis	Solution
Condensate not discharging	Inlet isolation valve closed	Open valve
	Pump inlet and outlet switched	Re-pipe
	Motive inlet and vent switched	Re-pipe
	Discharge isolation valve closed	Open valve
	Equalizer line isolation valve closed	Open valve
	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 completely 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 remains on	Motive steam valve leaks	Disassemble and clean or replace
	Mechanism not assembled properly	Assemble so the motive valve is inserted in motive seat
Steam leaks out of body	Body gasket leaks	Replace gasket
	Strainer gasket leaks	Replace gasket
	Plugs leak	Remove, add thread sealer and reinstall

Disassembly and Assembly Instructions

Disassembly:

1. Remove strainer cap using a closed wrench (27mm). Remove the strainer and strainer gasket.
2. Remove the bolt using a hexagon wrench (5mm). Move up and remove the cover and gasket from the body.
3. Fix the float arm section using an adjustable wrench. Remove the float using a spanner (17mm).
4. Remove two bolts attached to the cover using a spanner (13mm) and remove the valve.
5. Remove a set of the inlet valve using a closed wrench (19mm) and remove the inlet valve seat gasket.
6. Remove the vent valve seat using a spanner (24mm). Remove the vent valve seat gasket.
7. Remove the check valve from the body manually.

Assembly: Assemble in reverse order. Ensure the vent valve seat is tightened to 80 N·m, the inlet valve seat to 50 N·m, the float hexagon section to 15 N·m, and the cover bolts to 35 N·m. Always replace gaskets with new ones and apply paste on the entire surface and inside surface of the body gasket before assembly.