The Senate yesterday passed a two year pension funding relief bill that President Bush is expected to sign. Many considered the measure crucial to help employers facing huge cash demands on their pension plans. Some Senate Democrats voted against the measure saying it was unfair to plans operated by more than one employer. The bill's provisions are good for two years, during which Congress is supposed to study pension-funding problems and craft a long-term solution. The key element of the bill is a change in the way pension plans must compute their liabilities, which uses a formula based on the interest rate of the 30-year Treasury Bond.