LPS Reverse Buckling Disk

U.S. patents 5,996,605 and 6,178,983 apply. Other                          patents pending.

The Low                          Pressure LPS? Reverse Buckling Disk and SRB-7RS Safety Head

LPS Rupture Disk (Bursting Disc) Features:

• Solid Metal                            Design

• Low burst                            pressure from 5 psig (0.35 barg)

• Designed for gas,                            liquid or two phase service

• Fail Safe: Damage                            Safety Ratio ≤1

• Designed for                            non-fragmentation

• Vacuum/back                            pressure resistant

• High Operating                            Ratio: 90% of Minimum Burst Pressure

• Reverse Buckling                            Disk in sizes: 1"-8" (25 mm-200 mm)

• For installation                            in BS&B type SRB-7RS pre-torqued safety head

The LPS Rupture Disk (Bursting Disc) was developed to provide low                          burst pressures from 5 psig (0.35 barg) using reverse buckling rupture                          disk technology. The LPS Rupture Disk (Bursting Disc), combined with the SRB-7RS? Safety                          Head, provides accuracy and reliability. The LPS uses SAF? technology                          (Structural Apex Forming?) enabling very low burst pressures to be                          achieved with excellent opening characteristics.

LPS Rupture Disk (Bursting Disc) Material                          Options

The LPS Rupture Disk (Bursting Disc) is available in a range of                          corrosion resistant materials (see table on opposite page for details).

Standard disk materials are Nickel alloy 200,                          Stainless Steel grade 316, Inconel? (Nickel alloy 600), Monel? (Nickel                          alloy 400), Hastelloy? C-276, & Tantalum.

The  LPS disk includes an outlet side hinge to                          control fragmentation. Standard disk hinge  material is Stainless Steel                          grade 316 with alternates available upon  request.  Tef liners are                          offered with the type LPS Rupture Disk (Bursting  Disc) at burst pressures of 35 psig (2.4 barg) and higher.

Flow Performance/KR Values/Rupture Disk (Bursting Disc)                          Sizing

Flow resistance factor, "KR," may be used to                          determine the relieving capacity of a

system when using techniques such as those                          described in Crane Technical Paper No. 410.  Individual KR values                          have been established for both gas & liquid service for the LPS disk.                          These are experimentally determined at the BS&B Safety Systems, L.L.C.                          flow laboratory following ASME procedures and witnessed by ASME                          representatives. Care must be taken to use the correct value for sizing                          purposes. When  KR values are marked on the LPS disk tag, those for                          gas service are shown as "KRg," and those for liquid service are shown as                          "KRl."        

When using KR value for sizing calculations, the                          nominal pipe size (assuming schedule 40 pipe), of the vent system is used.                          When using "coefficient of discharge" sizing techniques, the Minimum Net                          Flow Area or Net Relief Area of the rupture disk (bursting disc) device is used.

MNFA Values and NRA Values

MNFA is expressed in square inches to facilitate                          sizing calculations in line with ASME practices. NRA is expressed in                          square centimeters for use when sizing in line with ISO, European                          Standards and forthcoming CEN practices.

Operating Pressure Ratio (Maximum                          Operating Pressure)   

LPS Reverse Buckling Disks can be operated to 90%                          of their minimum burst pressure. In other words, to 90% of the marked                          burst pressure less the burst tolerance.

Vacuum Resistance/Back Pressure                          Resistance

The LPS disk will resist vacuum without the need                          for an additional vacuum support. Back pressure resistance is limited to                          15 psig (1.03 barg) for disks rated to burst at 15 psig (1.03 barg) or                          less. For higher burst pressures, back pressure resistance is equal to the                          minimum burst pressure of the ordered LPS disk.

Burst Pressure Capability at 72oF (22oC)

Maximum Recommended                          Temperature

Hastelloy is a trademark of Haynes International                          Inc., Monel and Inconel are trademarks of Inco Alloys International. BS&B                          may use equivalent materials from other sources.

Note: Consult BS&B for applications where the                          disk may be rated with a

coincident temperature below 300oF/149oC                           (176oF/80oC for Hastelloy) but operated at a higher value. Special                          processing may be required.

Cycle Resistance/Temperature                          Influence/Service Life

The cycle resistance of the LPS disk is a function                          of the application operating conditions. If the operating pressure is                          static, (without pressure cycles), then as for all types of rupture                          disk  devices, the service life shall be maximized. If the operating                          pressure is mildly cyclic, such as the conditions of a sealed atmospheric                          tank under ambient temperature fluctuations, the LPS disk may resist in                          excess of 1000 cycles.

Under highly cyclic operating pressure conditions,                          the cycle life of the LPS disk is determined by the frequency and                          magnitude of pressure change from positive to negative differential. When                          all of the pressure cycling takes place within the operating pressure                          ratio of the LPS disk and at a positive differential pressure, the service                          life shall be maximized. Should the operating pressure cycle between full                          vacuum and positive pressure, the service life of the LPS disk can be                          anticipated at several hundred cycles.

Cycle and service life for every rupture disk (bursting disc)                          depends upon its unique application operating conditions. It is                          particularly  important to allow for the temperature's influence on                          burst pressure; if the rated burst temperature of the disk is selected too                          low, a higher actual temperature may reduce the disk burst pressure. Seek                          advice from BS&B Safety Systems regarding rated burst temperature.                          Other application factors including corrosion, erosion, abrasion, product                          build-up and vibration, affect the service life of a rupture disk (bursting disc) and must                          be considered by the user.

BS&B Safety Systems has developed "Rupture Disk (Bursting Disc)                          Manager" as a service tool that uses "in service" pressure and temperature                          information to generate alerts regarding maintenance replacement of                          rupture disks (bursting discs). Contact BS&B for more information.

Burst Pressure Tolerance                          Options

The approach to LPS disk burst tolerance depends                          upon which International Code is being followed. For disks to comply with                          the ASME Code, please select a "manufacturing design range" and the "burst                          tolerance" applicable to the required burst pressure. For disks to comply                          with European or ISO standards, please select either a Performance                          Tolerance or a min/max burst pressure. Alternate larger tolerances are                          indicated where a cost savings can be offered.

Burst Tolerance

Burst tolerance is the +/- range of pressure over                          which a rupture disk (bursting disc) can be expected to burst.  Burst tolerance is a                          function of LPS burst pressure, according to the table to the                          right.

Manufacturing Design Range (MDR)

Manufacturing design range is a range of pressure,                          always applied to the minus side of the user requested burst pressure for                          the LPS disk.

The standard LPS manufacturing design ranges are                          0%, -5%, -10%. For Tantalum, the MDR options are -5% and -10%                          only.

Performance Tolerance

Performance tolerance is being introduced to                          European and ISO codes. It is applied to the specified burst pressure as a                          percentage or a pressure quantity and includes all tolerances (both burst                          tolerance and manufacturing design range). Performance tolerance can also                          be expressed as a min/max burst pressure as shown below.

 *Select one, special requests for Performance                          Tolerance accepted.

Minimum/Maximum Burst Pressure

Minimum/maximum burst pressure is being introduced                          by European and ISO codes. Taking the specified burst pressure, select the                          preferred performance tolerance & convert to a min/max                          value.

For example: specified burst pressure of 3 barg and                          selected performance tolerance of +5%/-10%. This equates to a min/max of:

Minimum burst pressure (3 x 0.9) = 2.7 barg                          min

Maximum burst pressure (3 x 1.05) = 3.15 barg                          max

Special requests for min/max burst pressure                          accepted.

Sanitary/Aseptic Option

The LPS-S? disk is available for use in the SR-C?                        Safety Head providing low burst pressures for disks to be installed into                          sanitary/aseptic piping systems. The table below indicates the                          relationship between disk size, safety head size and the tri-clamp                          connection sizes at the inlet, outlet and mid-flange where the disk is                          installed within the safety head.

Installation in SRB-7RS? Safety                          Head

The                          LPS disk installed in an SRB-7RS? Safety Head permits the correct torque                          to be applied in the workshop before installation into the process. The                          asymmetric locating pins ensure centering and orientation of the disk                          within the safety head. The performance-proven metal-to-metal "bite-type"                          seal in the safety head (2"/50 mm size and above) assures a leak-tight                          assembly. When installed properly into the SRB-7RS Safety Head, the                          assembly can be removed, inspected, cleaned carefully then reinstalled                          without replacing the disk as the pre-torqued cap screws maintain the                          clamp load on the disk.

 The SRB-7RS Safety Head is used with other                          rupture disks (bursting discs) (types S-90?, JRS?, RLS? and FRS?) of the STA-SAF? System,                          Catalog 77-4001. The use of a common safety head facilitates upgrading                          from these rupture disks (bursting discs) to the superior technology of the LPS Rupture                          Disk and its higher pressure companion, the SKR Rupture Disk (Bursting Disc); see catalog                          77-4003.

Note: LPS disk petal is retained by the interaction                          of the disk hinge and the SRB-7RS? Safety                          Head.

U.S. Patent 4,751,938 and other international                          patents pending.

Inconel?  and Monel?  are registered                          trademarks of Inco Alloys International. Hastelloy?  is a registered                          trademark of Haynes International, Inc.

SRB-7RS Safety Head Dimensions

Related Products

For more information on other BS&B products,                          see Catalog 77-1010 for Burst Alert? Sensors compatible with the LPS                          Rupture Disk (Bursting Disc) and catalog 77-1016 describes the SmartDisk? wireless rupture                          disk monitoring system. Refer to our websites to learn                          more.