Schroedahl Type TDM Pump Protection Valves
Product Features
- Automatically modulating bypass function
- Forged housing material, carbon steel or stainless steel
- Special materials possible (e.g. Super Duplex)
- Internal operation (no external energy source required)
- Easy to install
- Low maintenance
- Suitable for all liquids
Applications
- Boiler feed water
- Condensate
- Chemical processes
- Extinguishing water
- Snow canons
Nominal Diameter: DN 25-300 / NPS 1-12
Pressure Class: PN 63-400 / Class 150-2500
Product Features
- Automatically modulating bypass function
- Forged housing material, carbon steel or stainless steel
- Special materials possible (e.g. Super Duplex)
- Internal operation (no external energy source required)
- Easy to install
- Low maintenance
- Suitable for all liquids
Applications
- Boiler feed water
- Condensate
- Chemical processes
- Extinguishing water
- Snow canons
Technical Data
| Nominal diameter | DN 25 – 300 / NPS 1 - 12 |
| Pressure class | PN 63 – 400 / Class 150 – 2500 |
| Temperature (max.) |
Up to 230 °C / 446 °F (other temperatures on request) |
| Housing material | 1.0460 / A105 1.0571 / LF2 1.4404 / F316L 1.4462 / F51 1.4501 / F55 |
| Housing type | Forged |
| Media | Liquids of all kinds (water, oils, chemicals and others) |
| Flanges | EN 1092-1, ASME B16.5, ISO 7005, JIS, JPI, welding ends of request |
| Designs | vertical installation, horizontal installation, manual start-up, enlarged nominal width of the bypass, degassing connection |
| Number of stages (max.) | 5 |
| Number of controlled stages (max.) | 5 |
| Operating range (max.) | Delta p up to max. 230 bar |
| Other | Bypass differential pressure up to 20-230 bar |
Function
The outlet main flow controls the non-return valve and positions it in proportion to the flow. The stem of the non-return valve transmits the motion via a lever to the bypass. The bypass system regulates the bypass flow in a modulating way and reduces the pressure to the bypass outlet pressure level without cavitation.
When the non-return valve is completely closed, the entire minimum flow is routed through the bypass. The bypass is fully closed when the nonreturn valve is in its upper position, thereby allowing full pump flow to the system.
Flow sensitive modulating bypass control
The non-return valve moves upwards with increasing main flow and downwards with decreasing flow. The non-return valve transmits this movement to the control lever.
The movement of the lever is transmitted via a piston to the multi-stage vortex plug. The minimum flow is then bypassed in a modulating way over several pressure reduction stages.
The TDM can be used for differential pressures from 20 bar up to 230 bar. The standard TDM design has a built-in bypass non-return function (~2 bar dp level required).
Manual bypass options for TDL valves
Depending on the plant design or additional requirements, various options can be selected for the start-up / warm-up side (A) and for the bypass side (B).
Option A:
One frequently used option is to feed low pressure flow to the process / boiler via the manual start-up. Either for the warm-up process or for heating the adjacent pumps/systems.
Option B:
Depending on the operating conditions of the system (dirt, certain load cases, etc.), special internal parts can be selected for the bypass. The valve is then supplied with the integrated optional bypass set. In this case the original internal parts for the bypass are supplied and installed after commissioning.
