  We present a magnetic-penetration-depth study on polycrystalline and granular
samples of SrPtAs, a pnictide superconductor with a hexagonal structure
containing PtAs layers that individually break inversion symmetry (local
noncentrosymmetry). Compact samples show a clear-cut s-wave-type BCS behavior,
which we consider to be the intrinsic penetration depth of SrPtAs. Granular
samples display a sample-dependent second diamagnetic drop, attributed to the
intergrain coupling. Our experimental results point to a nodeless isotropic
superconducting energy gap in SrPtAs, which puts strong constraints on the
driven mechanism for superconductivity and the order parameter symmetry of this
compound.
