Flowserve solves vaporisation
Flowserve, a global provider of fluid motion and control products, has launched its Flowserve QBQ LZ contacting-face mechanical seal for pumps in light hydrocarbon service at low vapour pressure margins.
A new model of the company’s QBQ seal, the QBQ LZ alters temperature and pressure dynamics in order to address the primary problem of vaporisation in light hydrocarbon service at low vapour pressure margins – that of light hydrocarbons natural tendency to flash from liquid to vapour at ambient pressure and temperature conditions, which can lead to dry-running of seal faces and premature seal failure and thus the missing of emissions and reliability objectives.
Featuring ‘Precision Face Topography’ and Flowserve’s patented wavy face seal design, the QBQ LZ is optimised for service with light hydrocarbons of specific gravity between 0.40 and 0.60. The ‘Precision Face Topography’ technology laser-machines smooth, low-amplitude patented wave patterns onto the seal face to create a stable hydrodynamic effect that changes the pressure profile on the seal faces and reduces friction and contact loads without increasing leakage.
Lower contact loads in turn reduce the temperature rise on the seal faces, which creates lower vapour pressure margins of between 5 and 50 psi (0.34 to 3.40 bar).
The seal’s reduced contact loading also minimises start-up torque and the face damage associated with start-ups and shutdowns, consequently extending seal life. The bi-directional QBQ LZ can be installed on either end of double-ended, double-suction pumps, without the need for pump modifications.
It satisfies all API 682/ISO 21049 design and qualification test requirements for single- and dual-arrangement seals.