c# property with using cache (expiration added)

    public static int CacheDyration = 10;
    /// <summary>
    /// Cached  Merchant table 
    /// </summary>
    public static Hashtable MerchantHash
    {
        get
        {
            Hashtable retValue = null;
            // Check if cache has Merchant saved
            if (HttpContext.Current.Cache["MerchantHash"] != null)
            { // Return cached version
                retValue = (Hashtable)HttpContext.Current.Cache["MerchantHash"];
            }
            else
            {
                // initializing  new instance,  you can change this initialization  with using BLL classes
                MerchantTableAdapter da = new MerchantTableAdapter();
                retValue = Hashmaker.Hash(da.GetData(), "merchant_id", "merchantname");
                if (retValue.Count > 0)
                {
                    HttpContext.Current.Cache.Insert("MerchantHash", retValue, null, Cache.NoAbsoluteExpiration, new TimeSpan(0, CacheDyration, 0));
                }

            }
            return retValue;
        }

        set
        { // Check if item is already in there
            if (HttpContext.Current.Cache["MerchantHash"] != null)
            {
                // Remove old item
                HttpContext.Current.Cache.Remove("MerchantHash");
            } // Place a new one
            HttpContext.Current.Cache.Insert("MerchantHash", value, null, Cache.NoAbsoluteExpiration, new TimeSpan(0, CacheDyration, 0));
        }
    }