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COSPECT® - Troublefree Pressure Reducing Valves

 COSPECT® - Troublefree Pressure Reducing Valves


COSPECT®’s built-in strainer, Super Cyclonical Effects Separator (SCE) and Free Float® steam trap help prevent scale, rust and condensate from entering the pressure reducing valve (PRV) or reaching the important interior parts.

In particular, the cyclone separator forcibly removes 98% of the condensate from the flow at the inlet side, thereby greatly reducing condensate-induced erosion of parts such as the main valve.

While the standard service life of a PRV for steam is often less than a few years, many TLV COSPECT® users are still using their COSPECT® PRVs more than 10 years after installation. Such long service life is a testimony to COSPECT®'s effectiveness in countering scale and condensate, some of the most common sources of problems for PRVs in steam systems.

 COSPECT® - Troublefree Pressure Reducing Valves

Common PRV Problems

Why Are There So Many Problems With Pressure Reducing Valves?

Examples of some of the problems with pressure reducing valves we often hear about are a lack of ability to control secondary pressure, safety valves blowing or the opposite, almost no steam flow, and that the secondary pressure drops. Many users have experienced that normal operation can often be restored by cleaning the interior of the pressure reducing valve, but they also find that the restored normal operation is only temporary.

As the fact that a thorough cleaning often restores normal operation might lead one to suspect, many of these kinds of problems with pressure reducing valves are due to the presence of foreign particulates such as scale or rust in the steam. There are a number of moving parts inside a pressure reducing valve, such as the piston and the pilot valve. A main cause of pressure reducing valve trouble is due to tiny particles of scale or rust getting into the gaps between these moving parts and preventing the parts from moving smoothly. It is also possible that in many cases tiny particles of scale are carried along in the condensate and merely installing a Y-strainer in front of the pressure reducing valve isn’t enough.

 COSPECT® - Troublefree Pressure Reducing Valves
Fig. 1 The build-up of scale and rust in PRVs can cause the piston to remain frozen.

Why is the Service Life of Pressure Reducing Valves So Short?

In some cases, normal operation cannot be restored even with cleaning. Many pressure reducing valves for steam have become unusable after having been in service for only a period of 2-3 years. There are many instances in which a main cause of the short service life of pressure reducing valves is the condensate entrained in the steam flow.

If large quantities of condensate are entrained in the steam that passes through the pressure reducing valve, depending on the velocity of the steam the droplets of condensate in the steam flow may hit the valve seat of the pressure reducing valve at extremely high speeds and cause erosion. This results in the sealing properties of the pressure reducing valve deteriorating over just a short period of time.

After suffering this kind of damage, no amount of cleaning can restore normal operation. The only alternatives in such a case are to replace either the damaged parts or the entire pressure reducing valve.

 COSPECT® - Troublefree Pressure Reducing Valves
Fig. 2 Condensate droplets cause erosion, which can reduce the sealing properties of a PRV.

COSPECT® Solution

Discover why COSPECT® offers such a Long Service Life

At TLV, numerous pressure reducing valve problems were studied and the two main causes of pressure reducing valve failure were traced to: moisture entrainment in the steam flow, and foreign matter such as rust and scale. In response to this, COSPECT® was designed with the following three built-in features:

  • Strainer
  • Separator
  • Steam Trap

Rust and Scale Cannot Reach Interior Parts Such as Piston and Main Valve

Foreign matter interfering with internal components and preventing smooth operation is one of the number one causes of pressure reducing valve failure. To prevent such interference in the COSPECT®, first the strainer removes rust and scale. Then remaining small particles of foreign matter are removed by the separator and discharged through the steam trap. This effectively prevents rust and scale from reaching the internal components, such as the piston and main valve, which are so critical for pressure reducing valve performance. Malfunction caused by build-up on moving parts is thus virtually eliminated.

Separation and Condensate Removal

TLV determined that an additional cause of pressure reducing valve failure, and a critical factor in service life, is erosion of the valve seat caused by condensate entrained in the steam flow. COSPECT®’s built-in separator and steam trap separate out and remove this condensate, thus protecting the valve seat from erosion.

Additionally, COSPECT®'s built-in steam trap allows for the discharge of any condensate that accumulates in the inlet piping during system shutdown. This helps prevent the formation of carbonic acid (corrosion) and helps protect the system from water hammer and other problems caused by condensate pooling.

Main Features of COSPECT® PRVs

 COSPECT® - Troublefree Pressure Reducing Valves
Fig. 3 The built-in screen, separator and Free Float ® steam trap help considerably lengthen service life.

Case Studies

COSPECT® Service Life is Testimony to Durability

Ever since COSPECT® first appeared on the market, TLV has followed-up on past installations in order to verify the product's performance.

In reviewing the service history of all the COSPECT®'s installed at one end-user’s site, it was found that over 70% of the 68 units in use had been in service for over 10 years ago. Of these, 12 units had been installed over 20 years ago.

Case studies

COSPECT® Service Life is Testimony to Durability


How to Improve Steam Quality

COSPECT® Pressure Reducing Valves with Built-in Separator and Steam Trap

Save maintenance time and installation costs by choosing the compact, easy-to-install COSPECT® package. The built-in cyclone separator and Free Float® steam trap use centrifugal force to remove approximately 98% of condensate entrained in steam. The steam is then further dried through pressure reduction to provide process steam almost 100% dry.

In addition to supplying high-quality dry steam, COSPECT® is built to last much longer than the average PRV. The separator and steam trap significantly extend its service life by reducing wear of parts.

Main Features of COSPECT® PRVs

 COSPECT® - Troublefree Pressure Reducing Valves  COSPECT® - Troublefree Pressure Reducing Valves  COSPECT® - Troublefree Pressure Reducing Valves



In addition to the basic COSPECT® model — COS-3, COS-16 and COS-21 — several other models are also available, such as a the compact SCOS, the M-COS for remote operation, and the ACOS for use with compressed air.

Products Product Details Appearance Specification Sheets
COSPECT® Pressure Reducing Valves
COS Pressure Reducing Valves for Process Steam View All
SCOS Compact Pressure Reducing Valves for Steam View All
ACOS Pressure Reducing Valves for Air View All
COSPECT® Control Valves
MC-COSR Multi-Control Valves View All
CV-COS Pneumatic Control Valves View All


New optional pressure gauge unit for selected TLV pressure reducing valves

Pressure adjustment can be bothersome work when pressure gauges are installed far from the product or, as is sometimes the case, not installed at all.
This new pressure gauge unit enables quick and easy confirmation of primary and secondary pressures at the valve, and simplifies manual valve adjustment.

It consists of a special holder plug to enable the installation of a pressure gauge of your choice.

Applicable models:

  • COS-3, COS-16, COS-21
  • COSR-3, COSR-16, COSR-21
  • A-COS-10, A-COSR-10
  • PN-COS-16, PN-COSR-16

Installation example

 COSPECT® - Troublefree Pressure Reducing Valves