Armstrong 30-DC Series automatic differential condensate controllers (DC) are designed to function on applications where condensate must be lifted from a drain point or in gravity drainage applications where increased velocity will aid in condensate drainage.

When lifting from the drain point, often referred to as syphon drainage, the reduction in pressure that occurs when the condensate is elevated causes a portion of it to flash back into steam. Ordinary steam traps, unable to differentiate between flash steam and live steam, close and impede drainage. Increased velocity with gravity drainage will aid in drawing the condensate and air to the DC. This increased velocity is caused by an internal steam by-pass, controlled by a manual metering valve, so the condensate controller will automatically vent the by-pass or secondary steam. This is then directed to the condensate return line or collected for use in other heat exchangers.

Connections and Materials

• Connections: Screwed NPT and BSPT
• Body: ASTM A105 Forged Steel
• Internals: All stainless steel—304
• Valve and seat: Hardened chrome steel—17-4PH
• Fittings: 3000# Carbon steel

Specifications and Dimensions

Model No.	33-DC	34-DC	35-DC	36-DC
Inlet & Outlet Connections	1" (25 mm)	1-1/4" (32 mm)	1-1/2" (40 mm)	2" (50 mm)
Secondary Steam Conn.	1/2" (15 mm)	3/4" (20 mm)	1" (25 mm)	1" (25 mm)
"A" (Diameter)	8" (203 mm)	8-5/8" (219 mm)	9-3/4" (248 mm)	11-7/8" (302 mm)
"B" (Height)	16-9/16" (420 mm)	19-1/4" (489 mm)	21-7/16" (544 mm)	23-7/8" (607 mm)
Weight lb (kg)	53 (24)	73 (33)	102 (46)	184 (83)
Maximum Operating Pressure, Sat. Steam	650 psi (44 bar)	650 psi (44 bar)	650 psi (44 bar)	650 psi (44 bar)
Maximum Allowable Pressure (Vessel Design)	1,080 psi @ 650°F (74 bar @ 343°C)	1,130 psi @ 650°F (78 bar @ 343°C)	1,015 psi @ 650°F (70 bar @ 343°C)	1,100 psi @ 650°F (76 bar @ 343°C)

Capacities

Model 33-DC Capacity

Model 34-DC Capacity

Model 35-DC Capacity

Model 36-DC Capacity

Installation, Start-Up and Operating Instructions

These instructions primarily cover the Condensate Controllers installed with the secondary steam being discharged back into the condensate return piping (See Figure 1 below). If the secondary steam discharge from the Controller is into a separate pipe header for re-use in other condensing units, the manual metering valve setting "D" may differ, depending upon the pressure of the secondary steam header.

Installation Recommendations

1. Locate Controller below equipment being drained when possible.
2. Full pipe size connections should be used to Controller inlet, outlet and secondary steam discharge.
3. Provide hand valves "E" and "B" as shown in Figure 1. These not only provide proper isolation for repair but are necessary when adjusting operation of Controller during initial start-up.
4. Provide a "test valve" hook-up ("C" in Figure 1). See Figure 2 for connection sizes and locations.
5. The manual metering valve ("D" in Figure 1), as supplied with the DC Controller, can be relocated to a horizontal position if necessary to reduce overall vertical installation height.

Start-Up & Operating Procedure

1. The following valve settings should be made on initial start-up of equipment. (Refer to Figure 1).

   • Valves "A", "B" and "E" open
   • Valves "C" and "D" closed With these valve settings, the Differential Controller is functioning as a standard inverted bucket steam trap. Continue to operate in this condition until system has reached operating conditions of pressure and temperature.

2. Close valve "B" on the condensate discharge of controller and open test valve "C". Condensate being discharged through the Controller is now observed at test valve piping to atmosphere. Note the cycle rate of condensate discharge. (This would be typical of the operation of a standard inverted bucket trap.)

Important

If the condensate discharge is continuous, never cycling, the Differential Controller selected may be too small for the required load.

3. Open manual metering valve "D" 1/4 turn from the full closed position. Observe the condensate discharge cycle rate. A definite increase in the cycle rate should occur over that observed in Step 2 above.
   • If no increase in cycle rate is observed with this setting, open the manual metering valve an additional 1/4 turn and again observe the discharge cycle rate. (Allow three or four minutes between changes for stabilizing effect.)
   • Continue this procedure until a definite increase in the condensate cycle rate is accomplished. (The normal adjustment setting for the manual metering valve will usually be from 1/4 to 1 full turn open.)

Note

If the secondary steam from the Controller is discharging into a separate header, the required setting of the manual metering valve may exceed 1 full turn open under low differential pressure (ΔP) conditions. Test as described above for correct setting.

4. Leave the manual metering valve set in the position as determined previously. Open valve "B" and close test valve "C".

The Differential Condensate Controller should now be functioning normally with the manual metering valve and secondary steam flow at the correct setting to provide the highest heat transfer efficiency.

Once the Differential Condensate Controller is set, the manual metering valve setting should not be changed. The handle of the valve should be locked in place to prevent valve tampering by unauthorized personnel. Should the manual metering valve be closed to isolate the Controller during repairs, record its opening position and return to same when putting Controller back in operation.

Test Valve Piping Size and Locations

30-DC Series Model	Test Valve Piping Size
32-DC	1/2"
33-DC	1/2"
34-DC	1/2"
35-DC	3/4"
36-DC	1"